Study of the interaction between components in hybrid CuZnAl/HZSM-5 catalysts and its impact in the syngas-to-DME reaction

García‐Trenco, Andrés; Vidal‐Moya, Alejandro; Martı́nez, Agustı́n

doi:10.1016/j.cattod.2011.06.034

Cited by 104 publications

(85 citation statements)

References 45 publications

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“…This is valid for both metallic catalysts and their physical mixtures with all the three solid acid catalysts under the applied operating conditions. This is in agreement with the experimental results showing that interactions between the two components of the catalyst requires a proximity [12] which is not met in the hybrids prepared by physically mixing the pre-pelletized components [8,9,13]. In the absence of poisons from the applied ultra-pure premixed synthesis gases, as well as the absence of iron and nickel carbonyl formation [28] within the tubings and the reactor (as confirmed by XPS analysis of the spent catalysts, not shown), and the lack of any meaningful differences among the stabilities of the CZA, alone and in the hybrid catalysts, sintering of copper crystallites is probably the main cause of the catalyst deactivation.…”

Section: Catalyst Deactivationsupporting

confidence: 91%

“…García-Trenco et al reported detrimental interactions between Cu/ZnO/Al 2 O 3 and HZSM-5 in the hybrid catalysts prepared by slurry or grinding methods, leading to a dramatic loss of the available Brønsted acid sites through partial exchange of zeolite protons by Cu 2+ and Zn 2+ , and blockage of the zeolite micropores by metallic catalyst particles [8]. The same group also found a correlation between the amount of the extra framework aluminum (EFAL) species on the external surface of the zeolite and the deactivation of the Cu-based methanol synthesis catalyst during the direct DME synthesis over the hybrid catalyst prepared by grinding [9,10].…”

Section: Ch 3 Oh(g)mentioning

confidence: 99%

“…Peng et al attributed the catalyst deactivation during slurry-phase direct DME synthesis to a detrimental interaction between the methanol synthesis catalyst and γ-alumina and hypothesized the migration of Cu-and Zn-contating species onto the acid catalyst as the likely mechanism [12]. Such adverse interactions between the metallic and the acid functions of the hybrid catalysts require an intimate solid-state contact between the two components, and hence, are highly dependent on the preparation method of the hybrid [8,9,12,13]. There have been several efforts to minimize these detrimental interactions in the hybrid catalysts with a high degree of interdispersion between their two components [11,14].…”

Section: Ch 3 Oh(g)mentioning

confidence: 99%

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Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

et al. 2016

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Direct dimethyl ether (DME) synthesis from synthesis gas is studied with regard to potential effects of methanol dehydration on methanol formation and copperbased catalyst performance. For this, the influence of the operating conditions (space velocity, temperature, pressure, time-on-stream and syngas composition) on activity, selectivity and stability of the catalyst was studied and compared for methanol synthesis and direct DME synthesis. The advantage of the direct over the two-step DME synthesis is apparent at conditions where syngas conversion to methanol is thermodynamically limited. However, under the applied operating conditions, results suggest that combining methanol synthesis and dehydration has a negative effect on the methanol formation kinetics. The origin of the observed phenomena is investigated by varying dehydration catalyst and by introducing dehydration products (DME and water) into the methanol synthesis feed. Choice of the solid acid catalyst does not seem to affect methanol formation, and DME is also found to be practically inert over the methanol synthesis catalysts. Water injection, on the other hand, led to a significant decrease in the methanol synthesis rate. Thus, formation of an additional amount of water through methanol dehydration might be an explanation for the lower methanol formation rate in the direct DME synthesis.

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Section: Catalyst Deactivationsupporting

confidence: 91%

Section: Ch 3 Oh(g)mentioning

confidence: 99%

Section: Ch 3 Oh(g)mentioning

confidence: 99%

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Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

et al. 2016

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“…For instance, methods comprising impregnation, co-precipitation, or sol-gel steps (or their combinations) [7,14,15] and even more sophisticated approaches leading to core-shell catalyst structures [16,17,18] have been reported. The most widely applied procedure, however, involves the simple physical mixing of the Cu-based methanol synthesis and acid methanol dehydration components [8,19,20,21,22]. The large number of variables involved in the different preparations and the lack of systematic studies has originated controversy about which method produces the most efficient catalyst.…”

Section: Introductionmentioning

confidence: 99%

The influence of zeolite surface-aluminum species on the deactivation of CuZnAl/zeolite hybrid catalysts for the direct DME synthesis

García‐Trenco

Martı́nez

2014

Catalysis Today

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ElsevierGarcía Martinez Feliu, A. (2014). The influence of zeolite surface-aluminum species on the deactivationof CuZnAl/zeolite hybrid catalysts for the direct DME synthesis. Catalysis Today. 227:144-153. doi:10.1016Today. 227:144-153. doi:10. /j.cattod.2013 AbstractIn this work, an original approach for preparing Cu-ZnO+H-ZSM-5 (Si/Al=15, denoted as Z5) hybrid catalysts displaying enhanced stability during the direct DME synthesis from syngas is presented. The adopted preparation strategy was based on the effective confinement of the copper catalyst within the pores of an SBA-15 silica carrier (d pore = 7.0 nm) prior to mixing with the acid zeolite. In order to maximize the Cu-ZnO interface area (where active Cu 0 sites are likely located) the walls of the SBA-15 silica were coated with a near-monolayer of ZnO (17 wt% Zn) prior the incorporation of copper (in concentrations of 10, 15, and 20 wt%) by the so-called ammonia-driving deposition-precipitation (ADP) method. Copper nanoparticles sizing 5-6 nm after H 2 -reduction (HRTEM) were effectively confined inside the SBA-15 mesopores (as supported by HAADF-STEM) for Cu loadings of up to 15 wt%. Higher Cu loadings (20 wt%) lead to large, XRD-visible, CuO nanoparticles residing out of the SBA-15 pores. The confined catalyst loaded with 15 wt% Cu (15Cu/Zn@S15) displayed the highest Cu 0 surface area (determined by N 2 O-RFC) and methanol synthesis activity. Then, hybrid catalysts based on this methanol synthesis function (15Cu/Zn@S15+Z5) were prepared in a 15Cu/Zn@S15:Z5 mass ratio of 2:1 by two methods: a) grinding the mixture of powders prior to pelletizing (method G), and b) mixing the pre-pelletized components (method M). Equivalent hybrids comprising a conventional coprecipitated Cu-ZnO-Al 2 O 3 (CZA) catalyst were also prepared for comparative purposes (CZA+Z5). The catalysts were evaluated for direct DME synthesis (533 K, 4.0 MPa) in runs lasting ca. 24 h. It was found that the confined 15Cu/Zn@S15+Z5 hybrids deactivated at a much lower rate than those based on CZA regardless the method of preparation. In turn, while conventional CZA+Z5 catalysts prepared by grinding (G) experienced a higher deactivation than that obtained by mixing (M) due to the contribution of detrimental interactions between the copper and zeolite components in the former, no differences in the deactivation rate were observed for the 15Cu/Zn@S15+Z5 hybrids prepared by grinding and mixing. The improved stability of these hybrid catalysts is accounted for by the inhibition of both detrimental interactions (by avoiding the direct contact of copper active sites and the zeolite surface) and extensive metal sintering (by limiting the extent of Cu 0 crystal growth) induced by the effective confinement of the Cu-based catalyst within the SBA-15 pores.

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“…Although an explanation for this loss in CO conversion at the highest -Al 2 O 3 is still not clear, it may be that the large alumina surface area absorbs some components from the Cu/ZnO surface, or migrates to the Cu/ZnO component blocking active methanol synthesis sites. 47,48 Overall, the best conditions are a Cu-ZnO/-Al 2 O 3 mass ratio of 1:2, which results in the highest CO conversion and DME yield (37 %, Table S5). …”

Section: Influence Of the Cu-zno@st/-al 2 O 3 Ratiomentioning

confidence: 99%

A one-step Cu/ZnO quasi-homogeneous catalyst for DME production from syn-gas

García‐Trenco

White

Shaffer

et al. 2016

Catal. Sci. Technol.

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ARTICLEThis journal is © The Royal Society of Chemistry 20xxJ. Name., 2013, 00, 1-3 | 1 Please do not adjust marginsPlease do not adjust margins a. Department of Chemistry, Imperial College London, South Kensington, London, UK, SW7 2AZ; c.k.williams@imperial.ac A simple one-pot synthetic method allows the preparation of hybrid catalysts, based on colloidal Cu/ZnO nanoparticles (NPs), used for the liquid phase synthesis of DME from syngas. The method obviates the high temperature calcinations and pre-reduction treatments typically associated with such catalysts. The hybrid catalysts are applied under typical industrially relevant conditions. The nature of the hybrid catalysts, the influence of the acid component, mass ratio between components, and Cu/Zn composition are assessed. The best catalysts comprise a colloidal mixture of Cu/ZnO NPs, as the methanol synthesis component, and -Al2O3, as the methanol dehydration component. These catalysts show high DME selectivity (65-70 %C). Interestingly, the activity (relative to Cu content) is up to three times higher than that for the reference hybrid catalyst based on the commercial Cu/ZnO/Al2O3 methanol synthesis catalyst. The hybrid catalysts are stable for at least 20 h time-on-stream, not showing any significant sintering of the Cu 0 phase. Post-catalysis,TEM/EDX shows that the hybrid catalysts consist of Cu 0 and ZnO NPs with an average size of 5-7 nm with -Al2O3 particles in close proximity.

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Study of the interaction between components in hybrid CuZnAl/HZSM-5 catalysts and its impact in the syngas-to-DME reaction

Cited by 104 publications

References 45 publications

Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

The influence of zeolite surface-aluminum species on the deactivation of CuZnAl/zeolite hybrid catalysts for the direct DME synthesis

A one-step Cu/ZnO quasi-homogeneous catalyst for DME production from syn-gas

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