A Surface Science Investigation of Methanol Synthesis over a Zn-Deposited Polycrystalline Cu Surface

Nakamura, Junji; Nakamura, Isao; Uchijima, Toshio; Kanai, Yuki; Watanabe, Taiki; Saito, Masahiro; Fujitani, Tadahiro

doi:10.1006/jcat.1996.0124

Cited by 125 publications

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“…A close correlation between the activity for methanol synthesis and the Cu 0 surface area has also been reported for conventional co-precipitated Cu-ZnOAl 2 O 3 catalysts [40,41,42]. Despite the precise nature of the active copper sites and the promoting role of ZnO x species are still controversial issues [43,44,45,46,47,48], it is generally consented that the active Cu sites are located at the Cu-ZnO x interface [34,43,49,50,51,52,53]. If this is so, the close parallelism between the activity and copper surface area found in the present study would suggest that a similar extent of Cu promotion by ZnO x was attained in the xCu/Zn@S15 catalysts, probably as a consequence of the near-monolayer dispersion of ZnO x on the SBA-15 surface, ensuring a high contact surface between confined Cu 0 nanoparticles and ZnO x species.…”

Section: Selection Of Methanol Synthesis Catalystmentioning

confidence: 65%

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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Section: Selection Of Methanol Synthesis Catalystmentioning

confidence: 65%

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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“…For CuZnAl catalysts, the similar correlation of catalytic activity and the reduction temperature is observed, which is also accounted for by the encapsulation of ZnO on the surface of Cu/ZnO [11]. In order to further clarify ZnO effects, Cu crystal surface modified by ZnO is also studied using surface science experiments [12,13] and theoretical calculation [14].…”

Section: Introductionmentioning

confidence: 61%

The Role of the Promoters in Cu Based Catalysts for Methanol Steam Reforming

Mao

et al. 2009

Catal Lett

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Effects of promoters such as zirconia and zinc oxide to copper catalysts have been studied in methanol steam reforming (MSR) reaction at 260°C. The catalytic activity and stability of copper are improved by promoters, especially zirconia. The results of S BET and S Cu represent that both promoters can increase S BET of catalysts from 0.26 to 0.28-0.99 m 2 /g and S Cu of them from 0.13 to 0.21-0.25 m 2 /g and XRD further illustrate that they can stabilize the crystal size of copper in process of reduction and reaction. Besides, XPS results indicate that both ZnO and ZrO 2 can stabilize Cu ? species and promote the catalytic activity for MSR. In addition, the rich surface hydroxyl species on ZrO 2 /Cu account for its superior catalytic performance to ZnO/Cu and Cu.

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“…A close correlation between the activity for methanol synthesis and the Cu 0 surface area has also been reported for conventional co-precipitated Cu-ZnO-Al 2 O 3 catalysts [40][41][42]. Despite the precise nature of the active copper sites and the promoting role of ZnO x species are still controversial issues [43][44][45][46][47][48], it is generally consented that the active Cu sites are located at the Cu-ZnO x interface [34,43,[49][50][51][52][53]. If this is so, the close parallelism between the activity and copper surface area found in the present study would suggest that a similar extent of Cu promotion by ZnO x was attained in the xCu/Zn@S15 catalysts, probably as a consequence of the nearmonolayer dispersion of ZnO x on the SBA-15 surface, ensuring a high contact surface between confined Cu 0 nanoparticles and ZnO x species.…”

Section: Selection Of Methanol Synthesis Catalystmentioning

confidence: 72%

A rational strategy for preparing Cu–ZnO/H-ZSM-5 hybrid catalysts with enhanced stability during the one-step conversion of syngas to dimethyl ether (DME)

García‐Trenco

Martı́nez

2015

Applied Catalysis A: General

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A Surface Science Investigation of Methanol Synthesis over a Zn-Deposited Polycrystalline Cu Surface

Cited by 125 publications

References 0 publications

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

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

The Role of the Promoters in Cu Based Catalysts for Methanol Steam Reforming

A rational strategy for preparing Cu–ZnO/H-ZSM-5 hybrid catalysts with enhanced stability during the one-step conversion of syngas to dimethyl ether (DME)

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