ZSM-5/SBA-15 versus Al-SBA-15 as supports for the hydrocracking/hydroisomerization of alkanes

[EN] Al-SBA-15 and ZSM-5/SBA-15 (ZSC) composite were synthesized following hydrothermal procedures in the presence of triblock copolymer Poly(ethylene glycol)- poly(propylene glycol)-poly(ethylene glycol) (Pluronic P123) and a mixture of tetrapropylammonium bromide (TPABr)/Pluronic P123 templates, respectively. Pt (0.5 wt.%)/Al-SBA-15 and ZSC bifunctional catalysts were then prepared by a wet impregnation methodology and investigated in the hydrocracking/hydroisomerization of n-decane. Pt/ZSC, containing a trimodal porous texture and high Bronsted acidity, exhibited hydrocracking activity while Pt/Al-SBA-15, showing merely Lewis acidity, was active for hydroisomerization. At 300 degrees C the conversion of n-decane on Pt/ZSC reached 98% and cracking selectivity was about 99%. Both catalysts were exhaustively characterized.This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 104.05-2014.21. CM aknowledges financial support by the Spanish Government-MINECO through "Severo Ochoa" (SEV 2012-0267) and CTQ2015-70126-R.Huyen, PT.; Nam, LTH.; Vinh, TQ.; Martínez, C.; Parvulescu, VI. (2018). ZSM-5/SBA-15 versus Al-SBA-15 as supports for the hydrocracking/hydroisomerization of alkanes. Catalysis Today. 306:121-127. https://doi.org/10.1016/j.cattod.2017.03.040S12112730

Co-Fe Clusters Supported on N-Doped Graphitic Carbon as Highly Selective Catalysts for Reverse Water Gas Shift Reaction

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Sustainable Chemistry & Engineering, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acssuschemeng.1c01401[EN] Graphitic carbons are suitable supports of metal nanoparticles with catalytic activity. In the present study, the preparation of N-doped graphitic carbon supporting clusters of Fe-Co alloys starting from biomass waste is reported. These sub-nanometric Co-Fe clusters supported on N-doped graphitic carbon at a metal loading below 0.2 wt % exhibit high activity for the selective hydrogenation of CO2 to CO. Operating at 500 degrees C and 10 bar with an H-2/CO2 molar ratio of 7 and a space velocity of 600 h(-1), a conversion of 56% with a selectivity of over 98% to CO, and remarkable stability over 30 h operation was obtained. Interestingly, analogous catalysts based on N-doped graphitic carbon with much higher Co-Fe loadings and an average particle size range of 1-5 nm exhibit only half of this activity, with similar CO selectivity. This contrasting behavior reveals the dramatic effect of the particle size on the catalytic activity. In comparison, SiO2 as support under similar conditions affords CH4 as the main product.Financial support by the Spanish Ministry of Science, Innovation, and University (Severo Ochoa and RTI2018.98237-B-CO1) and Generalitat Valenciana (Prometeo 2017/083) is gratefully acknowledged. L.P. thanks the Generalitat Valenciana for a Santiago Grisolia scholarship. BASF is thanked for financial support.Peng, L.; Jurca, B.; Primo Arnau, AM.; Gordillo, A.; Parvulescu, VI.; García Gómez, H. (2021). Co-Fe Clusters Supported on N-Doped Graphitic Carbon as Highly Selective Catalysts for Reverse Water Gas Shift Reaction. ACS Sustainable Chemistry & Engineering. 9(28):9264-9272. https://doi.org/10.1021/acssuschemeng.1c014019264927292

Isotopic H/D exchange on graphenes. A combined experimental and theoretical study

[EN] Adsorption of H-2/D-2 on graphene (G), graphene oxide (GO), single walled carbon nanotube (SWCNT), N-doped graphene [(N)G], and a sample of active carbon (C) has led to the detection of HD, indicating dissociative chemisorption of hydrogen on the surface of the material. The amount of HD detected follows the order G > SWCNT > GO similar to (N)G similar to C, G giving about five-fold higher H-2/D-2 adsorption and HD exchange level than SWCNT and about ten-fold larger values than that of the other samples. Quantum-chemistry calculations modeling a carbon atom vacancy on a G cluster estimates an activation barrier for H-2 dissociation of ca. 84 kJ/mol for a mechanism involving under coordinated carbon atoms at the defect site.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa SEV-2016-0267 and CTQ2015-69153-C2-R1) and Generalitat Valenciana (Prometeo 2013/014) is gratefully acknowledged. G. S. thanks the Scientific Division of SGAI CSIC for computing facilities.Sastre Navarro, GI.; Forneli Rubio, MA.; Almasan, V.; Parvulescu, VI.; García Gómez, H. (2017). Isotopic H/D exchange on graphenes. A combined experimental and theoretical study. Applied Catalysis A General. 547:52-59. https://doi.org/10.1016/j.apcata.2017.08.018S525954

Co-Fe Nanoparticles Wrapped on N-Doped Graphitic Carbons as Highly Selective CO2 Methanation Catalysts

[EN] Pyrolysis of chitosan containing various loadings of Co and Fe renders Co-Fe alloy nanoparticles supported on N-doped graphitic carbon. Transmission electron microscopy (TEM) images show that the surface of Co-Fe NPs is partially covered by three or four graphene layers. These Co-Fe@(N)C samples catalyze the Sabatier CO2 hydrogenation, increasing the activity and CH4 selectivity with the reaction temperature in the range of 300-500 degrees C. Under optimal conditions, a CH4 selectivity of 91% at an 87% CO2 conversion was reached at 500 degrees C and a space velocity of 75 h(-1) under 10 bar. The Co-Fe alloy nanoparticles supported on N-doped graphitic carbon are remarkably stable and behave differently as an analogous Co-Fe catalyst supported on TiO2.Financial support by the Spanish Ministry of Science, Innovation and University (Severo Ochoa and RTI2018.98237-B-CO1) and Generalitat Valenciana (Prometeo 2017/083) is gratefully acknowledged. L.P. thanks the Generalitat Valenciana for a Santiago Grisolia scholarship, and A.P. thanks the Spanish Ministry of Science and Education for a Ramon y Cajal research associate contract. V.I.P. thanks the UEFISCDI for continued funding through the projects PN-IIIP1-1.2-PCCDI-2017-0541 1/2018, PN-III-P4-ID-PCCF-20160088 17/2021, and PN-III-P4-ID-PCE-2020-1532. BASF is thanked for the financial support.Jurca, B.; Peng, L.; Primo Arnau, AM.; Gordillo, A.; Parvulescu, VI.; García Gómez, H. (2021). Co-Fe Nanoparticles Wrapped on N-Doped Graphitic Carbons as Highly Selective CO2 Methanation Catalysts. ACS Applied Materials & Interfaces. 13(31):36976-36981. https://doi.org/10.1021/acsami.1c055423697636981133

N-Doped Defective Graphene from Biomass as Catalyst for CO2 Hydrogenation to Methane

This is the peer reviewed version of the following article: B. Jurca, C. Bucur, A. Primo, P. Concepción, V. I. Parvulescu, H. García, ChemCatChem 2019, 11, 985, which has been published in final form at https://doi.org/10.1002/cctc.201801984. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] N-doped, defective graphene obtained by pyrolysis of chitosan at 900 degrees C under Ar exhibits catalytic activity for the Sabatier hydrogenation of CO2 to CH4 at temperatures about 500 degrees C with estimated turnover frequencies and activation energy values of 73.17s(-1) and 24.3 kcal x mol(-1), respectively. It has been found that this enhanced catalytic activity compared to other related doped defective graphenes derives from the presence of pyridinic N atoms that adsorbs CO2 forming carbamate-type adsorbates.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa, Grapas and CTQ2015-69153-CO2-R1) and Generalitat Valenciana (Prometeo 2017-083) is gratefully acknowledged. A.P. thanks the Spanish Ministry for a Ramon y Cajal research associate contract. V.I.P. kindly acknowledges UEFISCDI for financial support (projects PN-III-P4-ID-PCE-2016-0146, Nr. 121/2017, PN-III-P4-ID-PCCF-2016-0088 and PN-III-P1-1.2-PCCDI-2017-0541). Cristina Bucur thanks IFTM for the financial support.Jurca, B.; Bucur, C.; Primo Arnau, AM.; Concepción Heydorn, P.; Parvulescu, VI.; García Gómez, H. (2019). N-Doped Defective Graphene from Biomass as Catalyst for CO2 Hydrogenation to Methane. ChemCatChem. 11(3):985-990. https://doi.org/10.1002/cctc.201801984S98599011

Promotional Effects on the Catalytic Activity of Co-Fe Alloy Supported on Graphitic Carbon for CO2 Hydrogenation

[EN] Starting from the reported activity of Co-Fe nanoparticles wrapped onto graphitic carbon (Co-Fe@C) as CO2 hydrogenation catalysts, the present article studies the influence of a series of metallic (Pd, Ce, Ca, Ca, and Ce) and non-metallic (S in various percentages and S and alkali metals) elements as Co-Fe@C promoters. Pd at 0.5 wt % somewhat enhances CO2 conversion and CH4 selectivity, probably due to H-2 activation and spillover on Co-Fe. At similar concentrations, Ce does not influence CO2 conversion but does diminish CO selectivity. A 25 wt % Fe excess increases the Fe-Co particle size and has a detrimental effect due to this large particle size. The presence of 25 wt % of Ca increases the CO2 conversion and CH4 selectivity remarkably, the effect being attributable to the CO2 adsorption capacity and basicity of Ca. Sulfur at a concentration of 2.1% or higher acts as a strong poison, decreasing CO2 conversion and shifting selectivity to CO. The combination of S and alkali metals as promoters maintain the CO selectivity of S but notably increase the CO2 conversion. Overall, this study shows how promoters and poisons can alter the catalytic activity of Co/Fe@C catalysts, changing from CH4 to CO. It is expected that further modulation of the activity of Co/Fe@C catalysts can serve to drive the activity and selectivity of these materials to any CO2 hydrogenation products that are wanted.This research was funded by the Spanish Ministry of Science and Innovation and the University (Severo Ochoa SEV2021 and RTI2018.98237-B-CO1) and Generalitat Valenciana (Prometeo 2017/083). A.P. is the recipient of a Ramon y Cajal research associate contract awarded by the Spanish Ministry of Science and Innovation. L.P. thanks the Generalitat Valenciana for a Santiago Grisolia scholarship. BASF is thanked for financial support.Jurca, B.; Peng, L.; Primo Arnau, AM.; Gordillo, A.; Dhakshinamoorthy, A.; Parvulescu, VI.; García Gómez, H. (2022). Promotional Effects on the Catalytic Activity of Co-Fe Alloy Supported on Graphitic Carbon for CO2 Hydrogenation. Nanomaterials. 12(18):1-13. https://doi.org/10.3390/nano12183220113121

CO2 methanation catalyzed by oriented MoS2 nanoplatelets supported on few layers graphene

[EN] Powders of molybdenum disulfide platelets strongly grafted on graphene have been prepared by pyrolysis of ammonium alginate containing adsorbed various proportions of (NH4)(2)MoS4. After pyrolysis, formation of MoS2 supported on graphene was determined by XRD and electron microscopy and spectroscopic techniques. MoS2/G exhibits catalytic activity for the methanation of CO2, the performance being optimal at intermediate loadings. The catalytic activity of sharply contrasts with that of bulk MoS2 that promotes the reverse water gas shift, affording CO as the main product. Characterization of the spent MoS2/G catalyst shows the partial conversion of external MoS2 into MoO3. Comparison of the catalytic activity of MoS2/G with that of MoO3/G shows that the latter is less efficient, but more selective for CO2 methanation.Vasile I. Parvulescu kindly acknowledges UEFISCDI for financial support (project PN-III-P4-ID-PCE-2016-0146, Nr. 121/2017 and project PN-III-P1-1.2-PCCDI-2017-0541). Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69653-CO2-R1) and Generalitat Valencia (Prometeo 2017-083) is gratefully acknowledged. A.P. also thanks the Spanish Ministry for a Ramon y Cajal research associate contract.Primo Arnau, AM.; He, J.; Jurca, B.; Cojocaru, B.; Bucur, C.; Parvulescu, VI.; García Gómez, H. (2019). CO2 methanation catalyzed by oriented MoS2 nanoplatelets supported on few layers graphene. Applied Catalysis B Environmental. 245:351-359. https://doi.org/10.1016/j.apcatb.2018.12.034S35135924

Graphene oxide as a catalyst for the diastereoselective transfer hydrogenation in the synthesis of prostaglandin derivatives

[EN] Modification of GO by organic molecules changes its catalytic activity in the hydrogen transfer from i-propanol to enones, affecting the selectivity to allyl alcohol and diastereoselectivity to the resulting stereoisomers. It is noteworthy the system does not contain metals and is recyclable.Coman, SM.; Podolean, I.; Tudorache, M.; Cojocaru, B.; Parvulescu, VI.; Puche Panadero, M.; García Gómez, H. (2017). Graphene oxide as a catalyst for the diastereoselective transfer hydrogenation in the synthesis of prostaglandin derivatives. Chemical Communications. 53(74):10271-10274. doi:10.1039/c7cc05105kS1027110274537

N-Doped graphene as a metal-free catalyst for glucose oxidation to succinic acid

[EN] N-Containing graphenes obtained either by simultaneous amination and reduction of graphene oxide or by pyrolysis of chitosan under an inert atmosphere have been found to act as catalysts for the selective wet oxidation of glucose to succinic acid. Selectivity values over 60% at complete glucose conversion have been achieved by performing the reaction at 160 degrees C and 18 atm O-2 pressure for 20 h. This activity has been attributed to graphenic-type N atoms on graphene. The active N-containing graphene catalysts were used four times without observing a decrease in conversion and selectivity of the process. A mechanism having tartaric and fumaric acids as key intermediates is proposed.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa, Grapas and CTQ2015-69153-CO2-R1) and Generalitat Valenciana (Prometeo 2013-014) is gratefully acknowledged. Prof. Simona M. Coman kindly acknowledges UEFISCDI for financial support (project PN-II-PT-PCCA-2013-4-1090, Nr. 44/2014). Cristina Bucur acknowledges Core Programme, Project PN-480103/2016.Rizescu, C.; Podolean, I.; Albero-Sancho, J.; Parvulescu, VI.; Coman, SM.; Bucur, C.; Puche Panadero, M.... (2017). N-Doped graphene as a metal-free catalyst for glucose oxidation to succinic acid. Green Chemistry. 19(8):1999-2005. https://doi.org/10.1039/C7GC00473GS19992005198Alonso, D. M., Wettstein, S. G., & Dumesic, J. A. (2012). Bimetallic catalysts for upgrading of biomass to fuels and chemicals. Chemical Society Reviews, 41(24), 8075. doi:10.1039/c2cs35188aCherubini, F. (2010). The biorefinery concept: Using biomass instead of oil for producing energy and chemicals. Energy Conversion and Management, 51(7), 1412-1421. doi:10.1016/j.enconman.2010.01.015Christensen, C. H., Rass-Hansen, J., Marsden, C. C., Taarning, E., & Egeblad, K. (2008). The Renewable Chemicals Industry. 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