Study of operating variables in the transformation of aqueous ethanol into hydrocarbons on an HZSM‐5 zeolite

Aguayo, Andrés T.; Gayubo, Ana G.; Tarrío, Ana M; Atutxa, Alaitz; Bilbao, Javier

doi:10.1002/jctb.540

Cited by 108 publications

(26 citation statements)

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“…5,6 After the reaction no change in the XRD patterns and the surface areas of the catalysts was observed. The dependence on the partial pressure of EtOH was examined in the range 2.812.6 kPa at 673 K. The degrees of EtOH conversion and C2 = yield were always above 99%.…”

Section: ¹1mentioning

confidence: 96%

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Fast and Quantitative Dehydration of Lower Alcohols to Corresponding Olefins on Mesoporous Silica Catalyst

2011

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Ethanol, 1-propanol, 2-propanol, and 1-butanol were quantitatively dehydrated to the corresponding olefins on mesoporous silica MCM-41 catalyst. The reaction rates were high and no deactivation was observed for 50 h. Two reaction routes were suggested: the intermolecular dehydration of alcohol and subsequent decomposition of ether and the direct dehydration of alcohol.Utilization of bioethanol (bEtOH) as alternative to or as an additive of automobile fuel has rapidly expanded all over the world. This is of course a way to use renewable resources and suppress carbon dioxide emission, while another challenge is the conversion of bEtOH to various olefins and their use for production of chemicals and polymers.1 The latter would be very significant to fix carbon dioxide for the long-term period. Many efforts have, therefore, been devoted to development of selective conversion systems of bEtOH to ethene (C2 = ). It is widely known that the dehydration of alcohols is well catalyzed on various types of acids including modified aluminas, 2 supported heteropolyacids, 3 zeolites, 48 mesoporous materials, 9 and others, 10 but the activity and selectivity reported so far have been insufficient. For example, the reaction rates and the selectivity of C2 = on proton-or metal-modified zeolites should be improved, the selectivity is often restricted to ca. 96% due to strong acidic sites which cause oligomerization, polymerization, and fission of the produced lower olefins. 5,6 The various reactions in the zeolite pores finally result in coke formation and short lifetime. 57Niobium silicate 8 or silicotungstic acid supported on mesoporous silica 3 have been reported to show good selectivity for C2 = formation, but the reaction rates are not high due to the low surface areas. In addition, the low stability of loaded active components under high partial pressure of water would be a disadvantage for practical use.The novel acidic properties of mesoporous silica material, MCM-41 (M41), have been reported from the present 11,12 and other groups. 13 The acidity is not strong but unique to promote various selective catalyses. Our efforts have, therefore, been devoted to revealing the catalytic activity of M41 for the dehydration of EtOH, 1-and 2-propanol (PrOH), and 1-butanol (BuOH) to C2 = , propene (C3 = ), and butenes (C4 = ). We found the fast, quantitative, and stable catalyst can solve the above problems. The catalytic dehydration of alcohols is well known to be an easy heterogeneous catalytic reaction, but quantitative progress without deactivation is still necessary.M41 was prepared in the reported manner by using C 12 H 25 N(CH 3 ) 3 Br as the template and colloidal silica as the silica source.14 After calcination of M41 at 873 K for 6 h in air, the BET surface area and the BJH pore diameter determined by a N 2 adsorption measurement were 1010 m 2 g ¹1 and 2.12 nm, respectively. The hexagonal structure of resulting M41 was confirmed by appearance of 2ª = 2.580, 4.476, and 5.124 degree peaks in X-ray diffraction patterns (Cu K¡, ...

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Section: ¹1mentioning

confidence: 96%

“…96% due to strong acidic sites which cause oligomerization, polymerization, and fission of the produced lower olefins. 5,6 The various reactions in the zeolite pores finally result in coke formation and short lifetime. …”

mentioning

confidence: 99%

Fast and Quantitative Dehydration of Lower Alcohols to Corresponding Olefins on Mesoporous Silica Catalyst

2011

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“…3b, que mostra a seletividade para hidrocarbonetos leves, apresenta um comportamento oposto ao de hidrocarbonetos pesados (Fig. 3a), isto é, quanto menor a seletividade para eteno maior a seletividade para hidrocarbonetos pesados, indicando que o eteno, produto predominante entre os leves, é um intermediário para a formação dos hidrocarbonetos superiores [24]. O catalisador 2,5Ni/ZSM-5 que apresentou maior seletividade para os hidrocarbonetos pesados a 325 °C mostrou a menor seletividade na formação dos hidrocarbonetos leves, na mesma temperatura.…”

Section: Ensaios De Atividade Catalíticaunclassified

Conversão catalítica do etanol sobre catalisadores suportados em ZSM-5

Lima

Perez‐Lopez

2018

Cerâmica

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ResumoO petróleo, fonte de energia não renovável, é a principal matéria-prima usada na produção de derivados como combustíveis, lubrificantes e petroquímicos básicos. Neste contexto o etanol, uma matéria-prima renovável, torna-se fonte para a obtenção de hidrocarbonetos de maior valor agregado, tais como, benzeno, tolueno, etc. Este trabalho teve como objetivo avaliar o efeito de diferentes metais suportados em zeólita HZSM-5 para a conversão do etanol em produtos com maior valor agregado. Duas séries de catalisadores foram preparadas com diferentes metais e diferentes teores de Ni em HZSM-5 comercial. As amostras foram caracterizadas por área específica S BET , DRX, TPD-NH 3 e TPO. Os ensaios de atividade foram realizados em um reator tubular de leito fixo na faixa de temperatura entre 300 e 400 °C, usando etanol como reagente. Os resultados sugerem que o tipo e a quantidade de metal usado na modificação da zeólita HZSM-5 comercial influencia a seletividade para formação dos hidrocarbonetos superiores, bem como a temperatura de reação. A utilização de menores vazões favoreceu a formação de produtos pesados. A formação dos hidrocarbonetos superiores diminuiu ao longo da reação devido à deposição de carbono sobre a superfície do catalisador. Palavras-chave: catálise heterogênea, conversão do etanol, zeólita HZSM-5, catalisadores suportados, hidrocarbonetos superiores. Abstract The oil, a non-renewable energy source, is the main raw material used to produce derivatives such as fuels INTRODUÇÃOO petróleo tem sido responsável pelo fornecimento de um terço da energia primária consumida no planeta. Sua composição química, baseada em hidrocarbonetos de grande heterogeneidade molecular, abre caminhos para usos industriais mais especializados e sofisticados. Por isso, o petróleo é a principal matéria-prima empregada para produzir os derivados utilizados, tais como: combustíveis, lubrificantes e produtos petroquímicos [1]. Os compostos aromáticos são obtidos no processo de pirólise da nafta ou através da reforma catalítica (um dos processos envolvidos no refino de petróleo); sendo assim, a obtenção de hidrocarbonetos (em especial olefinas C 3 -C 4 e aromáticos) através da conversão do etanol é uma importante alternativa e tem atraído considerável interesse já há algum tempo [2,3].A condição de seletividade e a acidez da zeólita ZSM-5 são adequadas para a transformação do etanol em eteno, olefinas C 3 -C 4 ou em hidrocarbonetos [2,[4][5][6][7]. Também, observou-se, através de experimentos realizados para a reação de conversão de etanol, com diferentes metais impregnados sobre a zeólita ZSM-5, que o rendimento final de produtos BTX (benzeno, tolueno e xileno) é maior que no caso do uso da zeólita pura e, em alguns casos, a reação pode ser realizada a temperaturas relativamente baixas [8][9][10][11][12]. Van der Borght et al. [13] estudaram a conversão do etanol para a obtenção de hidrocarbonetos superiores utilizando HZSM-5 modificada com os metais Fe, Ni e Ga, onde os resultados foram comparados aos obtidos para a zeólit...

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“…Accordingly, the HZSM-5 zeolite is effective below 300 C and has been used with different modifications aimed at moderating its acid strength to avoid secondary reactions of ethylene conversion and to attenuate coke formation. [16][17][18][19][20] However, propylene and butene production takes place by transformation of ethylene through a oligomerization-cracking mechanism that requires temperatures above 350 C. [21][22][23] The main difficulty of this process is catalyst deactivation, although a distinction must be made between reversible deactivation (due to coke deposition) and the zeolite irreversible deactivation due to water content in the reaction medium (dealuminization). 24 In a previous study, the good performance of a catalyst based on a HZSM-5 zeolite treated with 0.2 M NaOH solution for 10 min has been proven.…”

Section: Introductionmentioning

confidence: 99%

Deactivation kinetics of a HZSM‐5 zeolite catalyst treated with alkali for the transformation of bio‐ethanol into hydrocarbons

et al. 2011

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The kinetics of deactivation by coke of a HZSM-5 zeolite catalyst in the transformation of bioethanol into hydrocarbons has been studied. To attenuate deactivation, the following treatments have been carried out: (i) the zeolite has been subjected to a treatment with alkali to reduce the acid strength of the sites and (ii) it has subsequently been agglomerated into a macro and meso-porous matrix of bentonite and alumina. The experimental study has been conducted in a fixed bed reactor under the following conditions: temperature, between 300 and 400 C; pressure, 1 atm; space-time, up to 1.53 (g of catalyst) h (g of ethanol) À1; particle size of the catalyst, between 0.3 and 0.6 mm; feed flowrate, 0.16 cm 3 min À1 of ethanolþwater and 30 cm 3 (NC) min À1of N 2 ; water content in the feed, up to 75 wt %; time on stream, up to 31 h. The expression for deactivation kinetics is dependent on the concentration of hydrocarbons and water in the reaction medium (which attenuates the deactivation) and, together with the kinetics at zero time on stream, allows the calculation of the evolution with time on stream of the yields and distribution of products (ethylene, propylene and butenes, C 1 -C 3 paraffins, and C 4 -C 12 ). By increasing the temperature in the 300-400 C range the role of ethylene on coke deposition is more significant than that of the other hydrocarbons (propylene, butenes and C 4 -C 12 ), which contribute to a greater extent to the formation of coke at 300 C.

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Study of operating variables in the transformation of aqueous ethanol into hydrocarbons on an HZSM‐5 zeolite

Cited by 108 publications

References 23 publications

Fast and Quantitative Dehydration of Lower Alcohols to Corresponding Olefins on Mesoporous Silica Catalyst

Fast and Quantitative Dehydration of Lower Alcohols to Corresponding Olefins on Mesoporous Silica Catalyst

Conversão catalítica do etanol sobre catalisadores suportados em ZSM-5

Deactivation kinetics of a HZSM‐5 zeolite catalyst treated with alkali for the transformation of bio‐ethanol into hydrocarbons

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