Effect of the property of solid acid upon syngas-to-dimethyl ether conversion on the hybrid catalysts composed of Cu–Zn–Ga and solid acids

Takeguchi, Tatsuya; Yanagisawa, Ken-ichi; Inui, Tomoyuki; Inoue, Masashi

doi:10.1016/s0926-860x(99)00343-9

Cited by 211 publications

(121 citation statements)

References 15 publications

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“…Water introduces diverse effects on both functions of the hybrid catalyst. For instance, high content of water caused by hydrogenation of a CO 2 -rich syngas over the metallic component of the hybrid catalyst enhances the deactivation of the Lewis sites of the acid component through strong water adsorption [15]. On the other hand, extra amount of water formed through methanol dehydration over the acid component of the hybrid, enhances the deactivation of the metallic component by assisting morphological changes and hydrothermal leaching of Zn and Al [11,16].…”

Section: Ch 3 Oh(g)mentioning

confidence: 99%

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: Ch 3 Oh(g)mentioning

confidence: 99%

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

et al. 2016

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“…In turn, lower reaction temperatures help in avoiding extensive coking and copper sintering that could jeopardize catalyst activity and lifetime. Furthermore, zeolites are more resistant than -Al 2 O 3 towards poisoning of acid sites by the water by-product [4,5,6]. Among the zeolites, the medium pore ZSM-5 (MFI) has been by far the most widely applied as the acid component in bifunctional DME synthesis catalysts [5,7,8,9,10,11], though other zeolites such as ferrierite, MCM-22 and its delaminated counterpart ITQ-2, IM-5, and TNU-9 have also been investigated [12,13].…”

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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“…This can be achieved using a hybrid catalyst in a two-step process. First, DME is hydrolyzed over a solid acid catalyst to methanol (MeOH) and then hydrogen is produced from methanol through steam reforming (SR) over Cu/ZnO/g-Al 2 O 3 [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…Mass production of DME can be achieved through coal or natural gas [1] or using methanol dehydration over solid acid catalysts such as alumina or H-ZSM-5 [7,[9][10][11]. As it can be inferred from the discussion above, DME !…”

Section: Introductionmentioning

confidence: 99%

NOx reduction on a transition metal-free γ-Al2O3 catalyst using dimethylether (DME)

2008

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NO 2 and dimethylether (DME) adsorption as well as DME and NO 2 co-adsorption on a transition metal-free g-alumina catalyst were investigated via in-situ transmission Fourier transform infrared spectroscopy (in-situ FTIR), residual gas analysis (RGA) and temperature programmed desorption (TPD) techniques. NO 2 adsorption at room temperature leads to the formation of surface nitrates and nitrites. DME adsorption on the alumina surface at 300 K leads to molecularly adsorbed DME, molecularly adsorbed methanol and surface methoxides. Upon heating the DME-exposed alumina to 500-600 K the surface is dominated by methoxide groups. At higher temperatures methoxide groups are converted into formates. At T > 510 K, formate decomposition takes place to form H 2 O(g) and CO(g). DME and NO 2 co-adsorption at 423 K does not indicate a significant reaction between DME and NO 2 . However, in similar experiments at 573 K, fast reaction occurs and the methoxides present at 573 K before the NO 2 adsorption are converted into formates, simultaneously with the formation of isocyanates. Under these conditions, NCO can further be hydrolyzed into isocyanic acid or ammonia with the help of water which is generated during the formate formation, decomposition and/or NCO formation steps. #

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Effect of the property of solid acid upon syngas-to-dimethyl ether conversion on the hybrid catalysts composed of Cu–Zn–Ga and solid acids

Cited by 211 publications

References 15 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

NOx reduction on a transition metal-free γ-Al2O3 catalyst using dimethylether (DME)

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