Poster session with coffee/drinks
pH INFLUENCE ON OBTAINING PT-BASED CATALYSTS ON GRAPHENE BY MICROWAVE- ASISTED METHOD
anisoara oubraham, felicia vasut, amalia soare, adriana marinoiu, daniela ion-ebrasu, mirela dragan
(presenter: Felicia Vasut)
Abstract: Keywords: pH changing, microwave reduction, catalyst, platinum, graphene oxide
Graphenic materials have unique and exceptional properties that derive from the structure and dimensionality. They have excellent specific surface, high thermal and chemical stability, also a great mechanical strength . Graphene and graphene oxides have been investigated as support material for many metals in order to produce catalyst. Using graphene and graphene oxides as support for the active metal has shown an improvement in catalytic activity when compared to the conventional support. This behavior may be explained by the high dispersion of active metal on the surface of graphene. Also, Pt or Pt metal alloy nano-catalysts supported on graphene sheets have higher electrocatalytic activity . Lately, there have been many methods used to prepare graphene with the aim of improving the overall yield. One of these methods is the microwaved assisted method. The paper presents the preparation of Pt/graphene oxide using microwave-assisted method. Were prepared samples in the same conditions using ethylene glycol like polar solvent but with different pH of the solution. The structure, morphology and properties were characterized using SEM/EDX, BET, infrared spectroscopy and XRD analysis for the prepared powder Pt/graphene oxide. The methods of analyzing samples reveals differences between the results, a clear influence of pH on Pt/graphene concentration and on catalysts microstructure.
1. P.V. Kamat PV, J. Phys Chem Lett., 2010, 520–527.
2. D. Chen, Li. Tang L, Chem Soc Rev, 2010, 39, 3157–3180.
OBTAINING Pt/GRAPHENE OXIDE NANOSHEETS UNDER MICROWAVES IRRADIATION USING REDUCING AGENTS
Felicia Vasut, Oubraham Anisoara, Amalia Maria Soare, Adriana Marinoiu, Daniela Ion-Ebrasu, Mirela Dragan
(presenter: Felicia Vasut)
Abstract: Since 2004, the field of graphene material has been constantly growing. Nanoparticles of metal on graphene nanosheet composites have attracted considerable interest because of the combined properties of metal nanoparticles with graphene [1-4]. There are different methods to synthesize Pt on graphene composites but using microwaves involves advantages like fewer stages and shorter time to produce. The paper presents obtaining Pt/graphene nanosheets by a microwave assisted reduction method. The method uses reduction of H2PtCl6 in the presence of ethylene glycol and other reducing agents (NaBH4 and KOH) and graphene oxide suspension. Samples were then microstructurally investigated using X-ray diffraction, SEM/EDX, BET and infrared spectroscopy.
DESIGN STRATEGY OF BIFUNCTIONAL CORE-SHELL CATALYSTS
Ainara Ateka, Ander Portillo, Pablo Rodriguez-Vega, Miguel Sánchez-Contador, Andrés Tomás Aguayo, Javier Bilbao
(presenter: Ander Portillo)
Abstract: The core-shell structure allows separating the reactions in the catalyst particle, generating therefore, a more suitable environment for each reaction. A macrokinetic model is herein proposed for reactions over catalysts with this structure, which considers the location of the reaction stages in each region of the catalyst particle. The work has been conducted studying the direct synthesis of dimethyl ether (DME) from syngas and CO2 on a CuO-ZnO-ZrO2@SAPO-11 catalyst. The reaction equipment, reactions scheme and experimental results considering deactivation have been described in previous works [1,2].
The model considers (Fig.1) that the reactions of methanol synthesis and water-gas-shift (WGS) take place in the CuO-ZnO-ZrO2 core region (metallic function); whereas methanol dehydration to DME, which displaces the thermodynamic equilibrium of the previous reactions occurs in the SAPO-11 shell region (acidic function). The kinetic parameters have been determined from the experimental results and the diffusion properties of the catalyst functions have been measured experimentally. The model predicts satisfactorily the experimental results in a wide range of conditions (10-40 bar;250-325 ºC; CO2/(CO+CO2),0-1;H2/(CO+CO2),2.5-4), and allows assessing the relevance of the diffusivity and the kinetic constants on each function, which will facilitate progressing towards the optimization of core-shell catalysts and the scaling-up of the reaction.
USE OF STAINLESS STEEL FOAMS AS STRUCTURED CATALYST FOR THE SYNTHESIS OF GRAPHENE RELATED NANOMATERIALS
Fernando Cazaña, Pilar Tarifa, Nieves Latorre, Víctor Sebastián, Eva Romeo, Miguel Ángel Centeno, Antonio Monzón
(presenter: Fernando Cazaña)
Abstract: The properties of graphene related materials (GRMs) make them as a promising material for many applications. GRMs can be obtained by different methods, being the decomposition of light hydrocarbons on catalytic substrates, also called Catalytic Chemical Vapour Deposition (CCVD), one of the most used to obtain large-size GMRs on structured supports1. In this work, we study of kinetics of growth of GRMs by catalytic decompostion of methane over stainless steel foams. After activation of the foam (Goodfellow, ref. FE243825)2, the reaction was carried out on a thermobalance at the following conditions: Temperature: 800-950 ºC, feed composition: %CH4: 3.6-48.9; %H2: 0-48.9, %N2: balance.
Carbon productivity along reaction (Fig. 1) increases progressively with temperature and %CH4 (Fig. 1a and 1b). However, there is observed maximum productivity at ca. 28.6 % of H2. These results are a combined result of: i) the evolution of the coverage of the metallic active sites by H2 and CH4, ii) the carbon atoms diffusion through the metallic nanoparticles, and iii) the deactivation of the metallic sites3. The kinetic model developed based in these assumptions allows explaining the influence of each stage of the GRMs formation.
LASER-ASSISTED CHEMISTRY TO DESIGN ADVANCED SINGLE-ATOM CARBON-BASED CATALYSTS
Ainhoa Martin, Gema Martinez, Alain R. F. Santiago, Reyes Mallada, Jose Luis Hueso, Jesus Santamaria
(presenter: Gema Mis Martinez)
Abstract: The on-going energy and chemistry transition characterized by the progressive electrification and the substitution of raw materials with alternative sources to decrease fossil fuel use, has driven a growing demand for the development of outstanding catalysts that radically change the current concepts of catalysis and related reaction mechanisms. Single-atom catalysts are recently emerging as a new frontier in heterogeneous catalysis science. Especially, carbon-based materials have proven to be excellent candidates for supporting single-atom catalysts due to their unique structural and electronic properties. However, fabricating single-atom catalysts, providing 100% metal centers dispersion under synthesis and catalysis conditions are highly challenging. This work is set on the establishment of the laser pyrolysis processing as one-pot and up-scale alternative in the synthesis of a single-atom catalyst with multiple catalytic active sites M-Nx (M= Fe) dispersed on a solid carbon surface. Spatial uniformity and high temperature (˃ 500ºC) in the reaction zone, short millisecond scale residence times, and high heating/cooling rates are the most important advantages of this strategy to control uniform atomic-scale distribution of the metal atoms. Finally, promising applications of the as-prepared catalysts as anode for sodium ion battery is described.
PHOTO-ASSISTED SYNTHESIS OF PLASMONIC METAL NANOPARTICLES USING TRANSPARENT POLYMERIC MICROREACTORS
Ismael Pellejero, Mikel Ardanaz, Santiago Reinoso, Luís M. Gandía
(presenter: Ismael Pellejero)
Abstract: Plasmonic metal nanoparticles (NPs), especially Au and Ag, have enormous interest for many practical applications such as catalysis, environmental remediation, biomedicine, etc. The continuous and environmentally friendly synthesis of such NPs is of great interest in order to improve reproducibility and mass production. Here we present a straightforward route for the continuous UV-light-driven synthesis of Au and Ag NPs with polyoxometalates (POMs) acting as photocatalysts and stabilizers. The microreactors used in this route are fabricated in a transparent polymer (PDMS) by a casting-dissolution method over 3D printed molds.
We have found that as-synthetized NPs are preferentially attached to the microreactor walls or easily formed and fabricated in continuous way depending on the type of POM and precursor concentrations. These interactions can be tuned by modifying the PDMS surface with hydrophilic or hydrophobic functional groups.
CATALYTIC OXIDATION OF EMERGING CONTAMINANTS IN WATER USING CU NPS SUPPORTED ON CELLULOSE REGENERATED BEADS
Alejandra Devard, Graciela Olmos, Claudia Taleb, Exequiel Nudel, Laura B. Gutierrez, Fernanda A. Marchesini
(presenter: Laura Gutierrez)
Abstract: Low concentrations of emerging contaminants can be found in water; they are usually bioactive and have a wide distribution and persistence in water bodies 1. The EC are associated with personal hygiene products, industrial and hospital wastes and therapeutic home consumed drugs (anti-inflammatories, analgesics, antibiotics, etc.). They can only be detected using sensitive analytical methodologies. Nowadays, ECs are removed from water by using different technologies such as Advanced Oxidation Processes (AOP) and wet catalytic oxidation (WAO). As a result, the design of catalytic formulations, which result active, selective, stable and low cost, is a hard challenge2.
In this work, a novel catalyst prepared with copper nanoparticles, synthetized with a full green protocol, using ascorbic acid as a reductant is presented. These CuNPs were impregnated in a support of regenerated cellulose beads3. Several copper impregnation conditions on the cellulosic structure were studied. This catalytic structured solid result easy to separate from the aqueous media after reaction. Phenol was used as EC probe molecule.
The catalytic results are very promising; due to the CuNPs supported on the cellulose beads resulted active and efficient for the phenol elimination. In fact, conversions higher than 80% with a final mineralization over the 50% were obtained.
DEVELOPMENT OF NOVEL Ni-Mg(Ce) CATALYSTS SUPPORTED ON BIOMORPHIC CARBON FOR CO2 METHANTION
Pilar Tarifa Sánchez, Fernando Cazaña Pérez, Víctor Sebastián Cabeza, José Ignacio Villacampa Elfau, Nieves Latorre Sierra, Eva Romeo Salazar, Antonio Monzón Bescós
(presenter: Antonio Monzon)
Abstract: In this work we present the results of the performance on the CO2 methanation reaction of Ni based catalysts supported on biomorphic carbons (BC) derived from cellulose. The catalysts were prepared using a one-step procedure using a biomorphic mineralization technique. This protocol allows obtaining good dispersions of the metallic nanoparticles over the biomorphic carbon.
The XRD patterns, see Figure 1, of the Ni-Mg and Ni-MgCe catalysts indicate that the presence of Ce decrease notoriously the average Ni particle size from 17 nm (Ni-Mg) to 8 nm (Ni-Ce). In addition, both catalysts present good textural properties, thus the BET area and pore volume are 228 m2/g and 0,56 cm3/g for Ni-Mg sample; and 403 m2/g and 0,39 cm3/g for Ni-MgCe. The activity results, see Figure 1B, show the most active (66% of CO2 conversion), selective to CH4 (94%) and stable catalyst is the NiMgCe/CDC, attaining the highest yield to CH4 (62%). The catalysts stability was measured along 8h of reaction, working at high WHSV (83600 h-1), at atmospheric pressure and using the stoichiometric feed ratio (H2/CO2=4/1). The NiMg/CDC catalyst shows a good initial performance but suffers deactivation along reaction due to the sintering of the Ni nanoparticles. The sintering process is consequence of the weak interaction developed between metallic nanoparticles and the carbonaceous support. The addition, of the Ce inhibits this phenomenon, increasing the intrinsic activity of the Ni nanoparticles.
SYNTHESIS OF METALLIC NANOCLUSTERS BY AN INNOVATIVE MICROWAVE SELECTIVE HEATING METHOD.
Roberta Manno, Victor Sebastian, Reyes Mallada, Jesús Santamaría
(presenter: Roberta Manno)
Abstract: Metallic nanoclusters, size smaller than 2nm, present excellent catalytic properties.1 Unfortunately, the tendency to agglomerate strongly affects their stability. We report an innovative procedure to synthesize clusters of Ag, Pd and Cu directly into the channels of mesoporous SBA 15 2. The mesoporous substrate impregnated by precursors was injected in a quartz tube and was surrounded by ice water (figure 1). In this way, microwave irradiation heated the reagents, promoting the synthesis of clusters. The ice water, transparent to microwave, rapidly reduced the temperature, avoiding further growing. The setup presented a high versatility, guaranteeing excellent results with all the metals analyzed.
PREPARATION OF ALCALASE BIOCATALYSTS COMBINING IMMOBILIZATION AND CHEMICAL MODIFICATION
Roberto Morellon Sterling, Fouzia Hussain, Sara Arana Peña, Sabrina Ait Braham, Jakub Kornecki, Djamel Edine Kati, Shagufta Kamal, Roberto Fernández Lafuente
(presenter: Roberto Morellón Sterling)
Abstract: Alcalase is a protease produced by a strain of Bacillus licheniformis which main enzymatic component is subtilisin. It has a great interest in many industrial processes like the enrichment of proteic foods, reduction of allergenicity, production of bioactive products, fine chemistry or even in the detergent industry. In this work, the use of different methods to improve the features of Alcalase via immobilization and further chemical modification is presented. Immobilization on glyoxyl agarose beads produced a significant stabilization. The chemical amination of the immobilized enzyme or the treatment of the enzyme with glutaraldehyde did not produce any further stabilization. However, in a step by step design, a great increasement in the enzyme stability was attained. On the other hand, the enzyme was hardly immobilized on aminated supports (due to its high IP) or in glutaraldehyde activated supports at high ionic strength, but it was immobilized on glutaraldehyde activated supports at low ionic strength. This suggested the existence of a synergy between the ionic exchange and the covalent attachment. The biocatalyst showed 50% activity against Boc-L-alanine-4-nitrophenyl ester while the activity against casein was doubled after immobilization. Some stability/activity features of all preparations will be discussed.
PREPARATION OF FICIN BIOCATALYSTS: COMBINED USE OF IMMOBILIZATION AND CHEMICAL MODIFICATION
Roberto Morellon Sterling, El-Hocine Siar, Sara Arana Peña, Jakub Kornecki, Roberto Fernández Lafuente, Nasreddine Zidoune
(presenter: Roberto Morellón Sterling)
Abstract: The use of proteases in the food industry is very interesting since specific proteases can perform some modifications in food impossible to obtain through chemical processes. In this work different approaches to immobilize the proteases contained in ficin extract on modified agarose supports were studied. Maximum loading experiments led to a drastic loss of activity, suggesting a non-optimal orientation of the enzyme. When ficin was immobilized in glyoxyl-agarose, an increment in stability of 40 folds respect to the free enzyme was achieved after 3 hours of immobilization, with at least 60% of expressed activity. Using just ion exchange followed by a treatment with glutaraldehyde led to the total inactivation of the enzyme. However, when the support was pre-activated with glutaraldehyde, a total immobilization was achieved at pH 7, maintaining a 60% of the initial activity after 24h of incubation at 55ºC. Effects were different depending on the immobilization pH, which shows the complexity of the mechanism involved in ficin immobilization on this support. However, a general increment of around 200% activity against casein was observed at pH 5, 7 and 9. Chemical modification was also assayed to enhance the immobilization or to improve the properties of the immobilized ficin.
EXPLOITING THE VERSATILITY OF GLUTARALDEHYDE CHEMISTRY IN ENZYME IMMOBILIZATION
El-Hozine Mr Siar, Roberto Mr Morellon-Sterling, Hadjer Dr Zaak, Roberto Prof FERNANDEZ-LAFUENTE
(presenter: Roberto Fernandez-Lafuente)
Abstract: Glutaraldehyde is a heterofunctional support employed for a long time in the preparation of immobilized enzyme biocatalysts [1,2]. This heterofunctionality opens the versatility of this immobilization method. This support has ion exchange capacity and hydrophobic groups, and also bears chemical reactivity that can generate covalent bonds.
These features make that glutaraldehyde may immobilize enzymes following very different protocols:
.- Adsorption of the enzymes on the aminated support via ion exchange followed by treatment with glutaraldehyde [3,4].
.- Use of preactivated supports at low ionic strength, where the first step of the immobilization remains the ion exchange [4,5].
.- Use of preactivated supports at high ionic strength to avoid ion exchange as first step of the immobilization, forcing the covalent attachment as the first immobilization step [5-7].
Thus, an enzyme immobilized using the same “chemistry” (glutaraldehyde) may exhibited very different final features.
COMPARISON OF SOME CATALYTIC FEATURES OF CALB, CALA AND EVERSA IMMOBILIZED ON OCTYL AGAROSE
Sara Arana Peña, Yuliya Lokha, Roberto Fernández Lafuente
(presenter: Sara Arana Peña)
Abstract: The main objective of the study was to compare different properties under diverse conditions of three different lipases, Lipase B from Candida antarctica (CALB), Lipase A from Candida antarctica (CALA) and Eversa Trasform (Eversa), immobilized on octyl-agarose beads (OC). The immobilization did not affect the activity versus p-nitrophenyl butyrate (pNPB) using Eversa, while using CALB the activity decreased to 80% and using CALA increased by more than seven folds. In terms of stability OC-Eversa was the most stable at pH 9, but the least stable at pH 5. Meanwhile, OC-CALA was the least stable at pH 9 and the most stable at pH 5 and 7, even better, at pH 7. In 90% of methanol, OC-CALB had much better stability than OC-Eversa and OC-CALA. In the presence of 90% dioxane, all of them maintained the activity and in 90% acetonitrile OC-CALA had a lower stability. This should be associated to differences on enzymes structure. Regarding the activity of derivatives, OC-Eversa was the most active vs. triacetin or pNPB, but the least active vs. methyl mandelate esters, while OC-CALA was the least active vs. triacetin and CALB was the least active vs. pNPB and the most active vs. methyl mandelate. Thus, depending on the specific reaction and the experimental conditions, these enzymes may offer different advantages and drawbacks.
STEP BY STEP LIPASES CO-IMMOBILIZATION USING OCTYL-GLYOXYL SUPPORTS: SOLVING THE PROBLEM OF LIPASES WITH VERY DIFFERENT STABILITIES
Sara Arana Peña, Carmen Méndez Sánchez, Nathalia Rios, Roberto Fernández Lafuente
(presenter: Sara Arana Peña)
Abstract: The co-immobilization of enzymes is increasingly popular in the scientific literature. The combined use of several lipases (combilipases) has increased the yields and reaction rates in biodiesel and oil hydrolysis, making interesting the co-immobilization of lipases. The use of heterofunctional glyoxyl-octyl (Gly-OC) supports could be a simple solution to resolve some problems arising from the co-immobilization of lipases (the necessity of discarding the most stable enzyme when the other lipase is inactivated). The sugested protocol uses Gly-OC in a step by step immobilization. First of all, the most stable enzyme is immobilized via interfacial activation and then covalently to the Gly-OC support. After the reduction of this first biocatalyst, the support loses its chemical reactivity and other lipase with a much lower stability can be immobilized on it via interfacial activation. This way, when the least stable enzyme is inactivated, it can be released from the support permitting the immobilization of a new batch of enzyme. This approach allows the most stable enzyme to be reused. Some problems found during the process will be discussed.
Toward microflow continuous production of high quality nanomaterials: Application in catalysis
Victor Sebastian, Isabel Ortiz de Solorzano, Laura Uson, Ane Larrea, Manuel Arruebo, Jesus Santamaria
(presenter: Victor Sebastian)
Abstract: The synthesis of nanocrystals with controlled sizes, shapes and composition has received great interests due to their unique properties, enhancing their performance in a variety of applications  The controlled synthesis of nanomaterials has attracted significant attention because the properties of nanocrystals are determined by their size, shape, structure and chemical composition. For instance, nanocrystals with different shapes expose different facets, which have different atomic arrangements. In catalysis, these structural difference leads to the variation in adsorption energy of reactants or intermediates, affecting notably the final selectivity and yield. . Microfluidic reactors offer an exquisite control of the reaction conditions and therefore embrace a great capacity to produce nanocrystals with well‐defined sizes, shapes and composition in a continuous fashion (Fig. 1).
Photocatalytic degradation of organic pollutants using Fe3O4/SiO2/TiO2-bimetalic nanocomposite
Salam Titinchi, Stefanie Bennett, Isaiah Johnson, Chiemeziem Oguayo Chiemeziem Oguayo, Hanna Abbo Hanna Abbo
(presenter: Salam Titinchi)
Abstract: The presence of organic pollutants in wastewater produced by various industry activities is an alarming matter for a safe environment and human health. For the last decades, conventional methods have been applied for the purification of water but due to industrialization these methods fall short. Advanced oxidation processes and their reliable application in degradation of many contaminants have been reported as a potential method to reduce and/or alleviate this problem. The incorporation of some metal nanoparticles such as magnetite nanoparticles as photocatalyst for Fenton reaction could improve the degradation efficiency of contaminants. Core/shell nanoparticles, are extensively studied because of their wide applications in the biomedical, drug delivery, electronics fields and water treatment.
The current study focus on the synthesis of bimetallic-doped Fe3O4/SiO2/TiO2 photocatalyst. Magnetically separable Fe3O4/SiO2/TiO2 composites with core–shell structure were synthesized by the deposition of uniform anatase TiO2 on Fe3O4/SiO2 using titanium butoxide as titanium source. The material was then further doped with silver and zinc. The metals were doped on TiO2 layer via hydrothermal method. The synergy between the materials has been shown to improve the photo-catalytic process and can overcome the separation difficulties associated with the powder form of the TiO2 catalyst, increase of the surface area and to upsurge the production of hydroxyl groups or reduced charge recombination.
The as-synthesized catalysts were characterized using various techniques viz. HR-TEM, SEM and EDS, XRD, IR, BET surface analysis and TGA. The average particles size was found to be 72 nm. Furthermore, the photocatalytic performances of the magnetic catalysts were assessed in comparison with that commercial titanium dioxide and with other photocatalysts for the degradation of methylene blue as a model pollutant using photochemical reactor under UV light . The results showed that the photocatalytic activity was enhanced using Ag/Zn-Fe3O4/SiO2/TiO2 photocatalyst compared to undoped photocatalyst Fe3O4/SiO2/TiO2.
Engineering 3D Fe/SiC monoliths for the SOLVENT-FREE production of dihydroxybenzenes in continuous flow
Asun Quintanilla, G Vega, E Madugra, J.A. Casas, P. Miranzo, M.I. Osendi, M. Belmonte
(presenter: Asun Quintanilla)
Abstract: Fe/SiC monoliths are feasible catalysts for the direct ring hydroxylation of phenol using hydrogen peroxide as oxidizing agent and water as reaction medium . This work explores the effect of the geometry and shape of channels on the catalytic performance of three-dimensional (3D) 0.52 wt.% Fe/SiC monoliths fabricated by Robocasting, a direct ink writing technique. Ceramic monoliths were prototyped with controlled 3D geometries (square, non-uniformed square and triangular channels) and manufactured with interconnected channels to increase external mass transfer while maintaining low-pressure drops . Table 1 shows the main physical properties of the monolith samples.
The hydroxylation reactions were conducted in an up-flow reactor operated during 72 h at: Cinlet,phenol = 0.32 M, 1:1 molar phenol/H2O2, T= 80 ºC, WCAT =3.80 g (3 stacked monolith), τ= 254 g h L-1 and water as solvent.
Interestingly, the channel geometry affected the Fe/SiC selectivity. The triangular cell monoliths, those with the highest surface-area-to-volume ratio (av), provided the highest selectivity to dihydroxybences (SDHB=98%) and the lowest one to tar (STAR=2%). On the other hand, the 3D customized monoliths exhibited similar phenol conversion (~23%) and hydrogen peroxide consumption (~85%).
KNOEVENAGEL CONDESATIONS OCCURED UNDER MICROWAVE IRRADIATION
Dariusz Bogdal, Szczepan Bednarz
(presenter: Dariusz Bogdal)
Abstract: Knoevenagel condensation which is the reaction of aldehydes and ketons with compounds containing active methylene groups (M) to form derivatives of benzylidene esters of malonic acid, acetoacetic acid and others, has been adapted to the synthesis of coumarins through the use
of reaction ortho-hydroxybenzaldehydes (A). Then lactonization follows after formation of a benzylidene derivative leads to the formation of coumarin (C) (Fig.1).
Since it was previously observed that Knoevenagel condensation were successfully carried out under solvent-free conditions as well as microwave irradiation, it was taken research on the synthesis of coumarins through Knoevenagel condensation under these conditions.
A number of effective methods of synthesis of coumarins and other heterocyclic derivatives under microwave irradiation will be presented.
Application of low temperature atmospheric microwave plasma to CO2 conversion.
Alexander Navarrete, Sergey Soldatov, Clara Marie Schmedt, Guido Link, John Jelonnek, Roland Dittmeyer
(presenter: Alexander Navarrete Muñoz)
Abstract: Since 2018 the Karlsruhe Institute of Technology has started activities to explore the feasibility of the use of microwave plasmas as a bridging technology to integrate chemical processes and green electricity. We will, in this opportunity, introduce the KIT Plasma Lab and the novel technology used to modulate the microwaves supply in order to control the temperature. Main results obtained for CO2 conversion will be discussed.
APPROACHES FOR THE MICROWAVE-ASSISTED SYNTHESIS OF METAL SULPHIDES CATALYSTS DERIVED FROM WASTED PIG BRISTLES
Alessio Zuliani, Camilla M Cova, Mario J Muñoz-Batista, Alina M Balu, Rafael Luque
(presenter: Alessio Zuliani)
Abstract: Moving our society dependence away from petroleum to renewable biomass resources is one of the most important gap to fill for the development of sustainable industries. With this aim, an extremely captivating challenge is the valorization of bio-wastes for the production of value added chemicals. Considering EUROSTAT data, it has been calculated that around 250 million pigs were slaughtered in the European Union in 2017. Since each slaughtered pig delivers ~0.9 kg of pig bristles, ~225 k tons of wasted pig bristles are produced annually. In the last year, we have been developing novel methods for the valorization of pig bristles through the utilization of microwave-assisted reactions. Specifically, we have described the microwave-assisted synthesis of Cu2S and Ag/Ag2S-hybrid carbon composites using wasted pig bristles as sulphur and carbon source. In order to validate the practical utilization of pig bristles-derived chemicals, different application were successfully tested. More in details, Cu2S carbon composites exhibited high activity in the photodegradation of a red pollutant dye under visible light irradiation. On the other hand, the electrocatalytic activities of Ag/Ag2S hybrid carbon composites were explored in the hydrogen evolution reaction (HER) performing linear sweep voltammetries.
Photothermal CO2 reduction to alkanes on Ni decorated TiO2 catalysts
Arturo Sanz Marco, Carlos Bueno, José Luis Hueso, Victor Sebastian, Francisco Balas, Jesus Santamaria
(presenter: Francisco Balas)
Abstract: The utilization of carbon dioxide (CO2) is becoming a subject of increasing importance, as a way to simultaneously face the problems of rising CO2 levels in the atmosphere and the progressive depletion of carbon-based resources. In this context, alkanes can be obtained from CO2 through Sabatier’s reaction and subsequent dimerization under light in the presence of photocatalysts [1,2]. Here, we have performed the CO2 hydrogenation to produce alkanes in a fixed bed photocatalytic reactor using high-radiance light emitting diodes (LED) in presence of Ni/TiO2 nanosized catalysts synthesized by means of a photodeposition procedure (Fig. 1).
The reaction was performed in a fixed bed reactor consisting in a prismatic quartz cell (50 x 10 x 5 mm, Teknokroma, Spain) loaded with ca. 60 mg Ni/TiO2 nanosized powder. The cell was simultaneously illuminated using 4.5-W LEDs (LedEngin, USA). A mixture of CO2 and H2 was injected through the bed and reaction products were tested at different periods using an Agilent 490 MicroGC. In conclusion, the final values of conversion and selectivity of CO2 into CH4 and C2H6 on a nanosized Ni/TiO2 catalyst depended on the irradiance conditions and the final temperature achieved in the reactor.
1. Meng et al. Angew. Chem. 2014, 126, 11662–11666
2. Bueno et al. Catal. Today 2019 (under review)
INTENSIFIED HEAT TRANSFER FOR STRONGLY EXO- OR ENDOTHERMIC REACTIONS WITH ADDITIVELY MANUFACTURED PERIODIC OPEN CELLULAR STRUCTURES
Giulia Littwin, Corinna Busse, Wilhelm Schwieger, Hannsjoerg Freund
(presenter: Giulia Littwin)
Abstract: Additively manufactured Periodic Open Cellular Structures (POCS) combine several favorable properties for the use as catalyst supports. Due to their high porosity and the three-dimensional connected network of struts POCS feature a low pressure drop and high thermal conductivity. This intensified heat transfer also allows for lower gas velocities and thereby extends the operation range in comparison to particle packings. Thus, especially in regards to strongly exothermic or endothermic reactions POCS show great potential for process intensification. By additive manufacturing, there are almost no limitations for the design of the structures, which also makes it possible to optimize the geometry depending on the application. For design and optimization, correlations for the heat transfer in POCS are necessary.
Therefore, in the present work heat transfer properties of POCS produced by selective electron beam melting (SEBM) with different unit cells (Diamond, Kelvin, Cubic) and various geometric parameters were investigated experimentally. Axial and radial temperature profiles in the heated structures were measured with multipoint thermocouples in a double pipe heat exchanger. From the temperature profiles, heat transfer coefficients were determined and correlated using a Nusselt-Reynolds approach. Depending on the unit cell and geometric parameters different heat transfer behavior was observed.
Microwave-Assisted Catalytic Dry Reforming of Methane
Ignacio de Dios García, Andrzej Stankiewicz, Hakan Nigar
(presenter: Hakan Nigar)
Abstract: Energy-efficient CH4-CO2 valorization to fuels and chemicals presents an urgent need considering the great variety of methane sources and the removal of greenhouse gases. Regarding the scientific and industrial importance, dry reforming of methane (DRM) is one of the well-studied approaches to the conversion of those abundant gases. DRM reaction produces syngas (H2+CO), which is a useful resource to manufacture of value-added products, such as higher alkanes and oxygenates through the Fischer-Tropsch process. Being an extremely endothermic reaction (ΔH=247.3 kJ/mol), DRM requires high operating temperatures, 800-1000ºC, to reach desirable conversion levels1,2. In this sense, the utilization of microwave (MW) as a nonconventional heating method will reduce energy consumption due to its selective energy transfer mechanism. In this present work, DRM reaction has been carried out in a custom-designed rectangular mono-mode MW applicator to improve reforming activities and reduce carbon deposition over several catalyst-support combinations (Pt/C, Ni/Al2O3, and the combination of Ni/Al2O3-SiC). The best heating and conversion performances under MW heating have been achieved with the combination of Ni/Al2O3-SiC having 5 wt.% Ni content. Conversions of CH4 and CO2 have been reached up to 90% at a GHSV of 500 mL/gcat.min, and microwave power input of 50W at 800ºC. No catalyst deactivation has been observed during the 6-hrs treatment.
MICROWAVE-ASSISTED METHANE VALORIZATION: IMPACT OF HEATING SOURCE ON PROCESS SELECTIVITY
Ignacio Julian, Jose Luis Hueso, Reyes Mallada, Jesus Santamaria
(presenter: Ignacio Julián)
Abstract: Natural gas is one of the main current energy alternatives. However, the use of methane as raw material is still limited due to transportation costs and the absence of efficient direct methane transformation routes into valuable chemicals which can compete with the oil based production of chemicals1. Main challenges in the direct methane conversion via non-oxidative (MNOC) and oxidative coupling (MOC) processes are fast catalyst deactivation due to coke deposition and low C2 selectivity, respectively.
Recently, microwave-assisted heating revealed its great potential in the field of gas-solid heterogeneous catalysis to shift the process selectivity towards the products of interest. The temperature gradient between the catalytic material and the comparatively colder surrounding fluid phase partially inhibits gas-phase reactions while promoting catalytic surface processes. This concept was proofed for a number of hydrocarbon conversion processes, e.g. isobutane dehydrogenation into isobutylene2 or ethylene epoxidation3.
This work addresses the evaluation of the effect of microwave-assisted heating (with respect to conventional heating) in methane valorization processes involving undesired gas phase reactions such the formation of polyaromatics, i.e. hard coke precursors for MNOC, and COx species during MOC.
GOLD-BASED PLASMONIC CATALYSTS WITH LED-DRIVEN FULL SPECTRUM PHOTORESPONSE
Bruno Bottega-Pergher, Javier Graus, Carlos J Bueno-Alejo, Marta Lafuente, Raul Arenal, Reyes Mallada, Jesus Santamaria, Jose L Hueso
(presenter: Jose L Hueso)
Abstract: Gold-based nanocatalysts have been traditionally selected for multiple homogeneous and heterogeneous reactions of interest involving redox processes. Likewise, greener routes involving more efficient reactors and the use of naturally available excitation sources have boosted the research on photocatalysts able to drive these chemical reactions upon excitation with multiple wavelength sources [1, 2]. In the present work we report on a novel synthesis approach that implies the in situ generation of triangular and prisms-shaped gold nanostructures with a full photocatalytic response in the UV-Vis-NIR range. These plasmonic structures have been in situ generated and deployed onto different oxide supports like ZnO, MgO or thermally treated hydrotalcites. Different LED excitation sources have been systematically selected to activate these hybrid materials either in liquid (selective hydrogenation of nitrophenol) or gas-phase (selective oxidation of carbon monoxide in the presence of hydrogen) reactions. The anisotropic shape of the gold triangles strongly favors the photocatalytic response in the visible-NIR window while the response in the UV-blue regions is strongly dependent on the electronic properties of the selected oxide supports.
AgBiS2 NANOCRYSTALS AS TiO2 PHOTOSENSITISER FOR SOLAR-DRIVEN REMOVAL OF PHENOLIC COMPOUNDS IN WASTEWATER
María Pilar Lobera, Jessica C. Ramirez, Raúl Boix, María Bernechea
(presenter: M. Pilar Lobera)
Abstract: Titanium dioxide (TiO2) is the prototypical semiconductor for photodegradation of persistent organic pollutants due to its chemical stability, harmlessness and low cost. However, TiO2starts absorbing at 400 nm and requires expensive high-intensity UV-lamps to achieve good efficiencies.
To reduce costs and improve the efficiency under solar light irradiation, in this work we have proposed to sensitize TiO2 with a semiconductor to increase the absorption in the visible and even the infrared range. Specifically, we propose AgBiS2 nanocrystals as sensitizers, and use these composites in the photodegradation of phenolic compounds under visible or solar light.1,2 Moreover, we have explored the effect of introducing different ligands on the surface of AgBiS2 nanocrytals. The electronic properties of colloidal nanocrystals depend not only on the nanocrystal size itself, but also on the surface chemistry. Indeed, the modification of the ligands on the surface allows to control the absolute energy levels of the material.This process is of great importance for photocatalytic applications since the use of different ligands can modify the position of the valence band or the conduction band with respect to the redox potential of molecules such as water or CO2 allowing to design new and better materials for photocatalysis.3
Rapid CO2 adsorption/desorption with radio-frequency heating
(presenter: Nikolay Cherkasov)
Abstract: CO2 capture helps to mitigate the negative impacts of global warming and climate change is expected to be dominated by amine liquid absorbers, however, at significant cost. This magnifies the significant drawbacks of their corrosivity, loss (via evaporation and decomposition), and high energy consumption for regeneration. Adsorption over solid materials eliminates corrosion and volatility, may decrease the energy consumption, provide for simpler operation, easier maintenance with higher flexibility.
In the work presented, we studied the performance of a siliceous mesocellular foam modified with polyethyleneimine amine absorber mixed with Fe3O4 magnetite pellets in an RF-assisted CO2 capture and regeneration. The materials inside a packed-bed reactor were RF-heated at 300kHz to facilitate CO2 desorption following its exposure to simulated post-combustion flue gas.
The working capacity of ~0.8 mmol g-1 was observed at during 20 min. adsorption cycles at 60C. The capacity increased with the temperature in the range 60 – 80°C, consistent with thermally enhanced gas diffusion. The RF-heated desorption was studied at various temperatures. The materials were heated to 105oC within 2.5 minutes with complete desorption in the temperature range of 95- 115°C. The regeneration rate was increased via RF heating compared to conventional heating.
MODEL FOR APROACHING A FLUIDIZED BED REACTOR-REGENERATION SYSTEM FOR MTO PROCESS
Tomás Cordero-Lanzac, Hector Vicente, Andrés T Aguayo, Pedro Castaño, Javier Bilbao
(presenter: Tomas Cordero-Lanzac)
Abstract: MTO process (methanol to olefins) is gaining interest for the sustainable production of olefins from abundant sources (carbon and natural gas) or biomass. However, the industrial process requires fluidized bed reactor-regenerator system with catalyst circulation due to the fast deactivation of the SAPO-34 catalyst . Consequently, efforts must be conducted to solve the inherent design hurdles considering the activity distribution of the catalyst particles (due to solid residence distribution) in both stages and the complex reaction scheme of MTO .
Trying to overcome this, an original model for designing a fluidized bed reactor-regenerator system is proposed in this work, where the kinetic parameters previously computed for the MTO process and catalyst deactivation are used . A discretization of the residence time distribution (RTD) profile (Fig. 1a) allows for individually studying the activity of the catalyst particles in both stages (Fig. 1b), the methanol conversion and the product distribution (Fig. 1c) for a given residence time. Thereby, a continuous operation of the MTO process in reaction-regeneration cycles can be simulated.
PRELIMINAR STUDY OF AN ORIGINAL PACKED BED MEMBRANE REACTOR FOR DME SYNTHESIS FROM CO2 CONTAINING SYNGAS
Pablo Rodriguez-Vega, Ainara Ateka, Ander Portillo, Andrés Tomás Aguayo, Javier Bilbao
(presenter: Ander Portillo)
Abstract: It has been determined by means of simulation that the use of a hydrophilic membrane reactor allows increasing the conversion of the CO2 co-fed together with syngas in the direct synthesis of dimethyl ether (DME) (environment-friendly fuel and vector for H2 and olefins), by displacing the thermodynamic equilibrium of the methanol synthesis, reverse WGS and methanol dehydration steps . This work overcomes the technological barrier of this initiative, by implementing a water permeable hydrophilic membrane into the Packed Bed Reactor (PBR). The catalytic bed composed of CuO-ZnO-ZrO2/SAPO-11 (ascertained to be active for CO2 hydrogenation and selective production of DME)  has been disposed inside a microporous LTA zeolite membrane, which is hydrothermally stable and selective to water permeance at the suitable operating conditions for the reaction, that is, high temperature and pressure (1.09·10-3 mol·m-2·s-1·Pa-1 at 300 ºC and 30 bar) . Using the same feedstock stream (H2+CO+CO2) as sweeping gas to remove the water permeated through the membrane, both the yield of DME (Fig. 1) and also the conversion of CO2 improve using a Packed Bed Membrane Reactor (PBMR).
Counteracting Sapo-34 Catalyst Deactivation In Mto Process With A Two Zone Fluidized Bed Reactor
Diego Zapater, Javier Lasobras, Jaime Soler, Javier Herguido, Miguel Menéndez
(presenter: Diego Zapater Bes)
Abstract: Olefins are key building blocks of the chemical industry, The production of olefins from alternative carbon sources includes as a promising process the reaction of methanol over SAPO-34 catalyst. The shape selectivity of this zeolite favours the production of C1-C4 hydrocarbons, but its fast deactivation by coke makes difficult a stable operation.
To reduce the deactivation effect, a two zone fluidized bed reactor (TZFBR) is proposed. In this reactor, reaction and regeneration take place at the same time.
Adaptation of MTO process in a forced periodic operation fixed-bed reactor
Héctor Vicente, Tomás Cordero-Lanzac, Andrés Tomás Aguayo, Ana Guadalupe Gayubo, Pedro Castaño
(presenter: Héctor Vicente)
Abstract: Forced periodic operation is a developing technique that involves dynamically varying operational parameters: temperature, pressure or inlet flow rates. The main objective of this operation is the improvement of conversion, selectivity or catalyst lifetime, as well as further understanding of the kinetic evolution of a process.
In this work, the methanol to olefins (MTO) process has been studied using a periodic operating reactor. The equipment consists of a jacketed fixed-bed reactor, which is capable of operating both isothermally or in heating-cooling cycles, as well as performing fast gas and liquid flow-rate changes.
A series of reactions have been performed in the reactor in both steady and unsteady conditions. The following experimental conditions ranges were used: temperature: 400-500 ºC; pressure of 1.5 bar; space time: 0.5-1.5 gcat h-1 molC-1; time of stream (TOS) of 6 h and methanol partial pressure of 0.8-0.9 bar. Results highlight higher olefin yield at 475 ºC runs, whereas CH4 and COx yields increase with temperature.
Extended catalyst lifetime was observed with temperature cycling, and greater olefin selectivity when cycling methanol and water feeds. From these runs, a preliminary MTO kinetic model has been proposed as described elsewhere for predicting periodic operation reaction.
Use of a fixed bed reactor with distributed feed to minimize thermal gradients for synthetic natural gas production
Paul Durán, Iván Esteban, Eva Francés, José Angel Peña, Javier Herguido
(presenter: Javier Herguido)
Abstract: This study is focused in methane production using electrolytic H2 from renewable sources and CO2 from biogas or sequestration processes. It is based in Sabatier reaction. The drawback is its high exothermicity ( -165.1 kJ/mol CO2), that can increase the yield to undesirable byproducts as CO or coke. To cope with this issue and reduce thermal gradients, it has been proposed a reactor with multiple feeds. Figure 1 (left) shows the configuration for this reactor. It has an upper entrance and 3 side inlets. One reactant is added through all 4 inlets, while the other only from above (main). The solid bed consists of 10%wtNi/Al2O3 catalyst (0.5 g) diluted in alumina (10 g). WHSV for molar ratio H2:CO2 = 4:1 was 0.75 h-1. Temperature effect has been tested from 250 to 400 °C. A comparison between single (conventional) and distributed feed shows that, as predictable, distributed feed reduce thermal gradients along the bed (Figure 1 center). However, this affects the yield to CH4, being higher with single feed: this configuration increases the contact time between gases and catalyst (Figure 1 right).
BIOGAS STEAM REFORMING AT LOW STEAM/CH4 RATIOS ON OPEN-CELL FOAM CATALYSTS
Pilar Tarifa, Nicola Schiaroli, Hoang Phuoc Ho, Francesca Ospitali, Antonio Monzón, Carlo Lucarelli, Giuseppe Fornasari, Angelo Vaccari, Patricia Benito
(presenter: Antonio Monzon)
Abstract: Clean biogas produced by anaerobic digestion can be valorized in delocalized small plants through reforming converting CH4 and CO2 into syngas. Steam addition reduces carbon formation, but two highly endothermic reactions, steam and dry reforming, are coupled, and large steam/CH4 (S/C) ratios suppress CO2 conversion. Herein, we propose the intensification of the steam reforming of clean biogas process, at low S/C ratios, over electrodeposited Rh and Ru-based catalysts on NiCrAl open-cell foams to enhance mass and heat transfer rates, also investigating the mechanism of carbon formation.
A thin (ca. 15μm) and homogeneous film of hydrotalcite-derived catalysts coat the NiCrAl foam surface (Fig 1a). The coating layer of MgO and MgAl2O4 contains well-dispersed Rh and Ru species . After reduction, metallic nanoparticles spread in the coating, even at high loadings, which are stable against sintering during tests. Biogas reforming under flexible conditions, modulating CO2 conversion and H2/CO ratio, is feasible over electrodeposited Rh structured catalysts (Fig 1b). Open-cell NiCrAl foams reactors operate at high WHSV, attaining high mass and heat transfer rates, and therefore high effectiveness factors; and also low carbon formation.
ZERO ENERGY CONSUMPTION CATALYSIS FOR INDOOR AIR POLLULANTS REMOVAL
Diego Velilla, Miguel Urbiztondo, Javier Herguido, Jesus Santamaria
(presenter: Miguel Urbiztondo Castro)
Abstract: Sick building syndrome (SBS) is a medical condition where people in a building suffer from symptoms of illness or feel unwell for the quality of the indoor air. This syndrome could be caused by inadequate ventilation, chemical pollutants from indoor or outdoor sources, biological pollutants, air recycled by fans, buildings located in a polluted urban area, etc. Volatile organic compounds (VOCs) would be the most common chemical pollutants and considering the effects on health, formaldehyde is one of the most significant.
Several publications show up to 90% of formaldehyde elimination rate at room temperature with catalyst with TiO2, Al2O3 or zeolites as supports of noble metals such as Au, Pd, Pt and Rh [1-2].
The main objective of this work is the VOCs elimination from indoor ambience to improve the air quality with zero energy consumption using this kind of catalysts. In particular, we propose the coverage of computers heatsinks with TiO2 or ZSM-5 impregnated or ionic exchanged with Pt. Microprocessors could be heated up above 50-60º C, hot enough to achieve the completed air pollutants elimination. Moreover, the forced-air from computer fans (air flow up to 100 m3/h) assure an intimate contact for the chemical reaction.
CORRELATION BETWEEN MOFs PREPARATION STRATEGIES AND THEIR CATALYTIC EFFICIENCY FOR DESULFURIZATION PROCESSES
Alexandre M. Viana, Susana O. Ribeiro, Diana Julião, Baltazar de Castro, Luís Cunha-Silva, Salete S. Balula
(presenter: Salete S. Balula)
Abstract: Porous metal-organic framework (MOF) materials such as UiO-66(Zr) and ZIF-8 were obtained by solvothermal and microwave advanced synthesis procedures. Their catalytic efficiency was investigated for oxidative desulfurization (ODS) processes using model diesel containing benzothiophene and dibenzothiophene derivatives. Some preparation parameters were identified as crucial to increase the catalytic efficiency of these heterogeneous catalysts. For example, the MWAS method seemed to play an important role in the catalytic performance of the UiO-66(Zr) material (desulfurization efficiency of 99.5% after 3 h), as well as in its recycle capacity. On the other hand, activation strategies of porous MOF structures were developed by incorporating catalytic active species and performing chloride treatments. The presenting studies are important guides to form catalytic MOFs that conciliate high structural stability and high recycle capacity; which make them promising materials for industrial applications.
Fig. 1. Desulfurization profiles using UiO-66(Zr) catalyst (acetonitrile as extraction solvent and H2O2 as oxidant, at 50 ºC). Vertical dashed lines indicate the beginning of the catalytic step by adding the oxidant.
Reference: A.M. Viana, S.O. Ribeiro, B. de Castro, S. S. Balula, L. Cunha-Silva, Materials, 2019, 12(18), 3009.
Catalytic hydrothermal liquefaction of food waste: benefits of solid acid-base catalysis
Heather LeClerc, Geoffrey Tompsett, Michael Timko, Andrew Teixeira
(presenter: Heather LeClerc)
Abstract: Millions of tons of food waste are thrown into landfills annually. Degradation products lead to a variety of detrimental wastes. Hydrothermal liquefaction (HTL) is an emerging technology in the waste-to-energy field that utilizes high temperature (T=300 ̊C) and pressure (P=3000 psi) to convert this waste into a bio-oil. With appropriate in-situ or downstream upgrading, this oil is suitable for the transportation and heating industries. HTL’s benefit is using complex, high water content feedstocks without inefficient drying steps.
Homogeneous catalysts have been utilized with HTL, however, pose process complexity and expense with separation and neutralization. Recently, solid catalysts, with acid- base characteristics have been used successfully with in-situ upgrading of food waste to bio-oil. [2,3]. Hydroxyapatite is a crystalline mineral found naturally in bones, and makes an attractive catalyst due to its acid-base sites and potentially renewable sources. This relatively inexpensive catalyst has preliminarily shown to result in the highest oil yield from food waste. In this work, a near supercritical liquid phase reactor is used with a food waste/catalyst slurry to drive the complex reactions. A bio-oil is generated with higher heating values approaching the range of diesel fuel and the catalyst shows excellent hydrothermal stability and regenerability.
1. Administration, F. a. (2019, May 23). Food Waste and Loss. Retrieved Aug 30, 2019
2.Maag, A. R. et al. Catalytic Hydrothermal Liquefaction of Food Waste Using CeZrO x. 1–14 (2018). doi:10.3390/en11030564
3.Long, J. et al. Comparative investigation on hydrothermal and alkali catalytic liquefaction of bagasse: Process efficiency and product properties. Fuel 186, 685–693 (2016).