Kinetic studies using temperature-scanning: the steam-reforming of methanol

Asprey, Steven P.; Wojciechowski, B. W.; Peppley, Brant A.

doi:10.1016/s0926-860x(98)00300-7

Cited by 75 publications

(43 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Among several rate expressions, assembled by Lee et al [10], this one was used directly or slightly modified in many other studies [11][12][13][14], in most cases in excellent agreement with the experimental data.…”

Section: Introductionmentioning

confidence: 95%

Steam reforming of methanol over copper-containing catalysts: Influence of support material on microkinetics

Frank

Jentoft

Soerijanto

et al. 2007

Journal of Catalysis

175

128

View full text Add to dashboard Cite

Steam reforming of methanol (SRM) was investigated over copper-containing catalysts supported on four different oxides and mixed oxides: Cu/ZnO/Al 2 O 3 , Cu/ZrO 2 /CeO 2 , Cu/SiO 2 and Cu/Cr 2 O 3 /Fe 2 O 3 . After observing slight differences in the way of catalyst aging and experimental exclusion of mass transport limitation effects, a detailed kinetic study was carried out at 493 K. The dependence of the reaction rate on the molar ratio of methanol and water was determined as well as the influence of addition of inert nitrogen and the main reaction products hydrogen and carbon dioxide to the reactant mixture. Although there were remarkable differences in the catalytic activity of the samples, the main mechanistic steps reflected in the rate law appeared to be similar for all catalysts. The reaction rate is mainly determined by the methanol partial pressure, whereas water is not involved in the rate determining step, except over Cu/Cr 2 O 3 /Fe 2 O 3 , where several differences in the chemistry were observed. Hydrogen and carbon dioxide were found to inhibit the reaction. These results were confirmed by a DRIFTS study at 493 K using an equimolar reactant mixture and an excess of 4:1 of water and methanol, respectively. The same surface species could be identified on each catalyst but neither kinetic modelling nor the DRIFTS spectra could give a clear answer if the reaction pathway occurs via a dioxomethylene or a methyl formate species as intermediate. Similar activation energies of SRM confirm the assumption, that the surface chemistry of SRM over copper-based systems is independent of the catalyst support material.

show abstract

Section: Introductionmentioning

confidence: 95%

Steam reforming of methanol over copper-containing catalysts: Influence of support material on microkinetics

Frank

Jentoft

Soerijanto

et al. 2007

Journal of Catalysis

175

128

View full text Add to dashboard Cite

show abstract

“…Because SRM is the sum of the other two reactions, the above processes are not independent [26]. The partial pressures of the reactants and products were calculated by assuming that the contribution of MD to the conversion was negligible.…”

Section: Kinetic Modelmentioning

confidence: 99%

“…The in situ characterization of Cu/ZnO under SRM activation and operating conditions revealed that the interaction of the Cu and ZnO phases has a pronounced effect on the catalytic activity [22,23]. For Cu/ZnO/Al 2 O 3 catalysts, high methanol conversions and low CO selectivities have been obtained [1,5,8,9,16] and kinetic analysis provided important information on the overall reaction mechanism [5,6,16,21,25,26]. Compared to the conventional ZnO or Al 2 O 3 -supported Cu catalysts, ZrO 2 -containing samples have shown increased activities and reduced CO levels for the SRM reaction [3,5,12,[27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Steam reforming of methanol over Cu/ZrO/CeO catalysts: a kinetic study

Mastalir

Frank

Szizybalski

et al. 2005

Journal of Catalysis

135

View full text Add to dashboard Cite

Steam reforming of methanol (SRM) was investigated over Cu/ZrO 2 /CeO 2 (CZC) catalysts prepared via a novel synthetic method based on coprecipitation and polymer templating. Structural characterization of the samples was performed by N 2 adsorption-desorption, N 2 O decomposition, and X-ray diffraction. The variation of the Cu loading resulted in an increased Cu crystallite size and a decreased specific surface area of the active particles. Catalytic investigations were carried out in a fixed bed reactor at 10 5 Pa, by applying a CH 3 OH:H 2 O = 1:1 ratio. The samples with Cu contents higher than 5 % exhibited good long-term stabilities and low CO levels during continuous operation. The kinetic model suggested for the transformation involved the reverse water-gas shift (RWGS) and methanol decomposition (MD), in addition to the SRM reaction. Kinetic measurements were accomplished in the temperature range 503-573 K and the experimental results could be well simulated. The highest methanol conversions and the lowest CO levels were observed in the temperature range 523-543 K. The apparent activation energies for the individual reactions were found to depend on the Cu content of the catalyst. Since the influence of mass transport limitations on the kinetic data could be excluded, it was established that the variation of the Cu concentration in the precursor material altered the microstructure of the Cu particles and, accordingly, the active Cu surface, which resulted in the formation of significantly different catalysts.Keywords: steam reforming of methanol, copper, zirconia, ceria, N 2 O chemisorption, long term stability, CO formation, kinetic model, reverse water-gas shift reaction, methanol decomposition, activation energy 1.IntroductionIn the past decade, considerable attention has been focused on the reduction of the significant emissions originating from mobile sources, such as internal combustion engines [1][2][3][4]. For environmental reasons, the development of proton-exchange membrane fuel cells (PEMFCs) has gained in increasing importance [5,6]. As compared with conventional heat engines, several advantages of fuel cell application have been established, including a higher efficiency and a more convenient operation, the absence of moving parts and the low emission of hazardous compounds [1,5]. The combustion of hydrogen in a fuel cell is regarded as a clean process, releasing energy and providing only water as an exhaust material [4,7,8]. However, hydrogen is not a natural energy source and must be generated by consuming a large amount of energy, either from natural gas or via the electrolysis of water [4]. Furthermore, for a fuel cell vehicle, the storage and the supply of hydrogen, a volatile and explosive gas, imposes mechanical problems and safety hazards on a commercial level [1,4,8].Several liquid fuel candidates have been discussed for on-board reforming, including methanol, ethanol, gasoline and diesel [1], of which methanol is considered the most favourable alternative [1,9]. Although mo...

show abstract

“…A equação (1) é a reação de reforma a vapor a qual produz o hidrogênio, no entanto a reforma a vapor de metanol produz uma pequena quantidade de monóxido de carbono (CO) o qual é produzido pela reação reversa do deslocamento do vapor de água, equação (1) (JIANG et al, 1993;PEPPLEY et al, 1999;ASPREY et al, 1999;AGRELL et al, 2002).…”

Section: Introductionunclassified

Estudo Da Seletividade Do Catalisador Industrial Aplicado Na Reforma a Vapor De Metanol

Neto¹,

Lenzi²,

Colpini³

et al. 2015

Anais Do XX Congresso Brasileiro De Engenharia Química

View full text Add to dashboard Cite

RESUMO -A busca por fontes renováveis de energia é crescente e necessária ao desenvolvimento da sociedade humana. O hidrogênio tem se mostrado uma fonte de energia promissora. Uma das formas de obtenção de hidrogênio que vem crescendo atualmente é a reforma de hidrocarbonetos, álcoois, éteres, entre outros. A reforma a vapor do metanol vem ganhando destaque uma vez que pode ser processada a temperaturas entre 250 o C à 350 o C, a pressão atmosférica e o metanol podendo ser produzido a partir da biomassa. A maior desvantagem dessa tecnologia é que no processo de reforma a vapor do metanol além do hidrogênio e do dióxido de carbono uma pequena quantidade, mas suficiente para prejudicar o funcionamento de células a combustível, de monóxido de carbono é produzida. O presente trabalho avaliou a melhor razão molar de água e metanol na alimentação de um reator de reforma a vapor a fim de se obter a melhor seletividade em um catalisador industrial.

show abstract

Kinetic studies using temperature-scanning: the steam-reforming of methanol

Cited by 75 publications

References 23 publications

Steam reforming of methanol over copper-containing catalysts: Influence of support material on microkinetics

Steam reforming of methanol over copper-containing catalysts: Influence of support material on microkinetics

Steam reforming of methanol over Cu/ZrO/CeO catalysts: a kinetic study

Estudo Da Seletividade Do Catalisador Industrial Aplicado Na Reforma a Vapor De Metanol

Contact Info

Product

Resources

About