Characterization and controlled combustion of carbonaceous deactivating species deposited on an activated carbon-based catalyst

The composition of the carbonaceous deactivating species (coke) deposited on a Pt and Pd supported P-containing activated carbon catalyst has been studied. These deactivating species were deposited on the catalyst during the hydrocracking of scrap tire pyrolysis oil at 400-500 degrees C, and it has been selectively characterized by means of temperature-programmed oxidation (TPO), temperature-programmed desorption/gas chromatography (TPD/GC) and laser desorption-ionization/mass spectroscopy (LDI/MS). In addition, the evolution of the textural properties and the acidity of the deactivated catalysts have been evaluated. The high thermal and oxidation resistance of the catalytic support has allowed to combust the coke in the TPO and calculate its intrinsic activation energy as a function of the extent of the combustion. Combined TPO and LDI/MS results have shown that an increase in the hydrocracking temperature attenuates the catalyst deactivation due to the hydrocracking of coke precursors. Coke aging, by evolving towards a more condensed structure, is also favored at higher hydrocracking temperatures. The combustion of the most condensed coke requires of higher temperatures than 375 degrees C, which hinders the complete regeneration of the activated carbon-based catalyst. (C) 2017 Elsevier B.V. All rights reserved

MAPO-18 Catalysts for the Methanol to Olefins Process: Influence of Catalyst Acidity in a High-Pressure Syngas (CO and H2) Environment

The transition from integrated petrochemical complexes toward decentralized chemical plants utilizing distributed feedstocks calls for simpler downstream unit operations. Less separation steps are attractive for future scenarios and provide an opportunity to design the next-generation catalysts, which function efficiently with effluent reactant mixtures. The methanol to olefins (MTO) reaction constitutes the second step in the conversion of CO2, CO, and H2 to light olefins. We present a series of isomorphically substituted zeotype catalysts with the AEI topology (MAPO-18s, M = Si, Mg, Co, or Zn) and demonstrate the superior performance of the M(II)-substituted MAPO-18s in the conversion of MTO when tested at 350 °C and 20 bar with reactive feed mixtures consisting of CH3OH/CO/CO2/H2. Co-feeding high pressure H2 with methanol improved the catalyst activity over time, but simultaneously led to the hydrogenation of olefins (olefin/paraffin ratio < 0.5). Co-feeding H2/CO/CO2/N2 mixtures with methanol revealed an important, hitherto undisclosed effect of CO in hindering the hydrogenation of olefins over the Brønsted acid sites (BAS). This effect was confirmed by dedicated ethene hydrogenation studies in the absence and presence of CO co-feed. Assisted by spectroscopic investigations, we ascribe the favorable performance of M(II)APO-18 under co-feed conditions to the importance of the M(II) heteroatom in altering the polarity of the M–O bond, leading to stronger BAS. Comparing SAPO-18 and MgAPO-18 with BAS concentrations ranging between 0.2 and 0.4 mmol/gcat, the strength of the acidic site and not the density was found to be the main activity descriptor. MgAPO-18 yielded the highest activity and stability upon syngas co-feeding with methanol, demonstrating its potential to be a next-generation MTO catalyst

A techno-economic and life cycle assessment for the production of green methanol from CO2: catalyst and process bottlenecks

The success of catalytic schemes for the large-scale valorization of CO2 does not only depend on the development of active, selective and stable catalytic materials but also on the overall process design. Here we present a multidisciplinary study (from catalyst to plant and techno-economic/lifecycle analysis) for the production of green methanol from renewable H2 and CO2. We combine an in-depth kinetic analysis of one of the most promising recently reported methanol-synthesis catalysts (InCo) with a thorough process simulation and techno-economic assessment. We then perform a life cycle assessment of the simulated process to gauge the real environmental impact of green methanol production from CO2. Our results indicate that up to 1.75 ton of CO2 can be abated per ton of produced methanol only if renewable energy is used to run the process, while the sensitivity analysis suggest that either rock-bottom H2 prices (1.5 $kg−1) or severe CO2 taxation (300$ per ton) are needed for a profitable methanol plant. Besides, we herein highlight and analyze some critical bottlenecks of the process. Especial attention has been paid to the contribution of H2 to the overall plant costs, CH4 trace formation, and purity and costs of raw gases. In addition to providing important information for policy makers and industrialists, directions for catalyst (and therefore process) improvements are outlined.The authors gratefully acknowledge financial support from the King Abdullah University of Science and Technology (KAUST). T. Cordero-Lanzac and A.T. Aguayo acknowledge the financial support received from the Spanish Ministry of Science and Innovation with some ERDF funds (CTQ2016-77812-R) and the Basque Government (IT1218-19). T. Cordero-Lanzac also acknowledges the Spanish Ministry of Education, Culture and Sport for the award of his FPU grant (FPU15-01666). A. Navajas and L.M. Gandía gratefully acknowledge the financial support from Spanish Ministerio de Ciencia, Innovación y Universidades, and the European Regional Development Fund (ERDF/FEDER) (grant RTI2018-096294-B-C31). L.M. Gandía also thanks Banco de Santander and Universidad Pública de Navarra for their financial support under ‘’Programa de Intensificación de la Investigación 2018’ initiative

Activation of n-pentane while prolonging HZSM-5 catalyst lifetime during its combined reaction with methanol or dimethyl ether

[EN] This work explores the synergies during combined reactions of n-pentane (nC5) with oxygenates (methanol or dimethyl ether, OX). The experimental runs have been carried out in a packed bed reactor at 500 °C, using a high silica HZSM-5 zeolite-based catalyst with different oxygenate-to-n-pentane (OX/nC5) ratios in the feed. A significant enhancement of the n-pentane conversion occurs for low OX/nC5 ratios in the feed (0.1¿0.25), especially when using dimethyl ether (DME). In addition, the presence of n-pentane reduces the rate of catalyst deactivation by coking during the conversion of oxygenates. These results have been explained on the grounds of a mechanistic interaction between the reactants: (1) the fast formation of methoxy and olefin intermediates from oxygenates, particularly from DME, could explain the promotion of n-pentane cracking, by facilitating the activation of the alkane by hydrogen transfer reactions; (2) the attenuation of deactivation during the conversion of oxygenates could be related to a lower extent of the arene cycle in the dual-cycle mechanism (limiting the polymethylbenzene formation). The analyses of used catalysts by means of temperature-programmed oxidation and confocal fluorescence microscopy have pointed out the higher reactivity of DME than that of methanol also for yielding coke structures.TC-L, ATA, PC and JB acknowledge the financial support received by the Spanish Ministry of Economy and Competitiveness with some ERDF funds (CTQ2016-77812-R,CTQ2016-79646-P), the Basque Government (IT1218-19) and the European Commission (HORIZON H2020-MSCA RISE-2018. Contract No. 823745). TC-L also acknowledges the Spanish Ministry of Education, Culture and Sport for the award of the FPU grant (FPU15-01666) and the additional mobility grant (EST17-00094). CM and AC acknowledge national and regional funding (MICINN/GVA) through `Severo Ochoa"(SEV-2016-0683), RTI2018-101033-B-I00 and AICO/2019/060 and financial support from EU by ERC-AdG-2014671093(SynCatMatch) and from the Fundacion Ramon Arecesthrough a research contract of the "Life and Materials Science" program. The authors also thank Dr. Ricardo Andrade of the SGIker of UPV/EHU for the support provided with the CFM technique.Cordero-Lanzac, T.; Martínez, C.; Aguayo, AT.; Castaño, P.; Bilbao, J.; Corma Canós, A. (2022). Activation of n-pentane while prolonging HZSM-5 catalyst lifetime during its combined reaction with methanol or dimethyl ether. Catalysis Today. 383:320-329. https://doi.org/10.1016/j.cattod.2020.09.01532032938

Activation of n-pentane while prolonging HZSM-5 catalyst lifetime during its combined reaction with methanol or dimethyl ether

This work explores the synergies during combined reactions of n-pentane (nC5) with oxygenates (methanol or dimethyl ether, OX). The experimental runs have been carried out in a packed bed reactor at 500 °C, using a high silica HZSM-5 zeolite-based catalyst with different oxygenate-to-n-pentane (OX/nC5) ratios in the feed. A significant enhancement of the n-pentane conversion occurs for low OX/nC5 ratios in the feed (0.1−0.25), especially when using dimethyl ether (DME). In addition, the presence of n-pentane reduces the rate of catalyst deactivation by coking during the conversion of oxygenates. These results have been explained on the grounds of a mechanistic interaction between the reactants: (1) the fast formation of methoxy and olefin intermediates from oxygenates, particularly from DME, could explain the promotion of n-pentane cracking, by facilitating the activation of the alkane by hydrogen transfer reactions; (2) the attenuation of deactivation during the conversion of oxygenates could be related to a lower extent of the arene cycle in the dual-cycle mechanism (limiting the polymethylbenzene formation). The analyses of used catalysts by means of temperature-programmed oxidation and confocal fluorescence microscopy have pointed out the higher reactivity of DME than that of methanol also for yielding coke structures.TC-L, ATA, PC and JB acknowledge the financial support received by the Spanish Ministry of Economy and Competitiveness with some ERDF funds (CTQ2016-77812-R,CTQ2016-79646-P), theBasque Government (IT1218-19) and theEuropean Commission(HORIZON H2020-MSCA RISE-2018. Contract No. 823745). TC-L also acknowledges the Spanish Ministry of Education, Culture and Sport for the award of the FPU grant (FPU15-01666) and the additional mobility grant (EST17-00094). CM and AC acknowledge national and regional funding (MICINN/GVA) through ‘Severo Ochoa” (SEV-2016-0683), RTI2018-101033-B-I00 and AICO/2019/060 and financial support from EU byERC-AdG-2014-671093(SynCatMatch) and from the Fundación Ramón Arecesthrough a research contract of the “Life and Materials Science” program. The authors also thank Dr. Ricardo Andrade of the SGIker of UPV/EHU for the support provided with the CFM technique.Peer reviewe

Activation of n-pentane while prolonging HZSM-5 catalyst lifetime during its combined reaction with methanol or dimethyl ether

This work explores the synergies during combined reactions of n-pentane (nC) with oxygenates (methanol or dimethyl ether, OX). The experimental runs have been carried out in a packed bed reactor at 500 °C, using a high silica HZSM-5 zeolite-based catalyst with different oxygenate-to-n-pentane (OX/nC) ratios in the feed. A significant enhancement of the n-pentane conversion occurs for low OX/nC ratios in the feed (0.1−0.25), especially when using dimethyl ether (DME). In addition, the presence of n-pentane reduces the rate of catalyst deactivation by coking during the conversion of oxygenates. These results have been explained on the grounds of a mechanistic interaction between the reactants: (1) the fast formation of methoxy and olefin intermediates from oxygenates, particularly from DME, could explain the promotion of n-pentane cracking, by facilitating the activation of the alkane by hydrogen transfer reactions; (2) the attenuation of deactivation during the conversion of oxygenates could be related to a lower extent of the arene cycle in the dual-cycle mechanism (limiting the polymethylbenzene formation). The analyses of used catalysts by means of temperature-programmed oxidation and confocal fluorescence microscopy have pointed out the higher reactivity of DME than that of methanol also for yielding coke structures.TC-L, ATA, PC and JB acknowledge the financial support received by the Spanish Ministry of Economy and Competitiveness with some ERDF funds (CTQ2016-77812-R,CTQ2016-79646-P), theBasque Government (IT1218-19) and theEuropean Commission(HORIZON H2020-MSCA RISE-2018. Contract No. 823745). TC-L also acknowledges the Spanish Ministry of Education, Culture and Sport for the award of the FPU grant (FPU15-01666) and the additional mobility grant (EST17-00094). CM and AC acknowledge national and regional funding (MICINN/GVA) through ‘Severo Ochoa” (SEV-2016-0683), RTI2018-101033-B-I00 and AICO/2019/060 and financial support from EU byERC-AdG-2014-671093(SynCatMatch) and from the Fundación Ramón Arecesthrough a research contract of the “Life and Materials Science” program. The authors also thank Dr. Ricardo Andrade of the SGIker of UPV/EHU for the support provided with the CFM technique

Continuous aqueous phase reforming of wastewater streams: A catalyst deactivation study

This paper reports on the catalytic performance and deactivation in aqueous phase reforming of wastewater streams for H2 production. Brewery wastewater was chosen as representative of this type of effluent. The effect of catalyst support textural characteristics was evaluated using an activated carbon and different modified supports obtained by infiltration and carbonization of a phenolic resol resin into activated carbon. The effect of active phase was evaluated using Pt and PtRe catalysts with different metal molar ratio. At short time on stream values, Pt catalysts supported on modified activated carbon showed higher H2 production than those supported on unmodified activated carbon, indicating that a lower microporosity facilitates the transport of reactants to catalytic active sites and release of reaction products. Bimetallic PtRe catalysts showed higher activity than Pt, particularly using a metal molar ratio of 1:1, which yielded the highest H2 production (117.2 μmol min−1). Despite the different catalysts tested, early and significant deactivation was observed. The characterization of used catalysts allows postulating the adsorption of organic species and/or coke-like matter deposition on the catalysts surface as main causes of deactivationThe authors greatly appreciate financial support from Spanish MINECO (CTQ2015- 65491-R) and Comunidad de Madrid (BIOTRES-CM P2018/EMT-4344). A. S. Oliveira thanks the Spanish MINECO a research grant (BES-2016-077244)

Continuous aqueous phase reforming of a synthetic brewery wastewater with Pt/C and PtRe/C catalysts for biohydrogen production

This work investigates H2 production through aqueous phase reforming (APR) of synthetic brewery wastewater in a continuous fixed bed reactor with Pt and PtRe (3 wt %) catalysts supported on activated carbon. The influence of weight hourly space velocity (WHSV) and superficial Ar gas flow velocity (VAr) was assessed for the sake of optimisation, while reaction temperature and pressure were maintained at 225 °C and 28 bar, respectively. H2 production was found to be higher using the PtRe catalyst at the lowest WHSV (0.03 h−1) and highest VAr (0.8 cm s−1). The comparison of the maximum H2 production obtained in this work (27.9 μmol min−1) with other treatment processes shows the potential of the application of APR process for H2 production from brewery wastewater. Despite the different reaction conditions tested, the catalysts showed deactivation with time on stream, which was related to the formation of solid deposits on the surface of the catalysts. Therefore, future research should be related to the development of more stable catalysts, strategies that avoid deactivation by coking and regeneration processesThe authors greatly appreciate financial support from Spanish MINECO ( CTQ2015-65491-R ) and Comunidad de Madrid ( BIOTRES-CM P2018/EMT-4344 ). A. S. Oliveira thanks the Spanish MINECO a research grant ( BES-2016-077244 )