Direct Conversion of Syngas to Light Olefins over a ZnCrO<sub><i>x</i></sub> + H-SSZ-13 Bifunctional Catalyst

Huang, Yuxuan; Ma, Hongfang; Xu, Zhiqiang; Qian, Weixin; Zhang, Haitao; Ying, Weiyong

doi:10.1021/acsomega.1c00751

Cited by 14 publications

(7 citation statements)

References 38 publications

(97 reference statements)

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“…A further decrease in the GHSV from 7000 to 4200 mL/g cat h leads to a further increase in methane selectivity to 38%, and a further decrease in C 2 = –C 4 = , C 2 –C 4 paraffin and C 5+ selectivities. The CO conversion at 4200 mL/g cat h was found to be as high as 44%, which is among the highest values reached by OX-ZEO catalysts in the current literature. − ,− ,− ,,,,− The increasing conversion is caused by the higher contact time, which also leads to enhanced hydrogenation of the hydrocarbons. A correlation between GHSV and CO 2 formation was not observed, as for all space velocities tested in this study a CO 2 selectivity of around 42% was observed.…”

Section: Resultsmentioning

confidence: 85%

“…One important aspect that could lead to an enhanced understanding is to identify the influence of the metal oxide components on the product distribution. Notably, many OX-ZEO catalysts reported in the literature consist of ZnCr oxides as one catalyst component. ,,− For example, Arslan et al obtained a selectivity of 70% for tetramethylbenzene together with a CO conversion of 37% and a CO 2 selectivity of about 50% using a ZnCr 2 O 4 spinel oxide jointly with H-ZSM-5 in a stream of H 2 deficient syngas . Likewise, a combination of SAPO-34 with a series of ZnCr oxides with varying Zn/Cr ratios ranging from 4:1 to 1:3 revealed a significant effect of the metal oxide composition on the OX-ZEO process .…”

Section: Introductionmentioning

confidence: 99%

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Influence of the ZnCrAl Oxide Composition on the Formation of Hydrocarbons from Syngas

et al. 2022

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The conversion of syngas into value-added hydrocarbons gains increasing attention due to its potential to produce sustainable platform chemicals from simple starting materials. Along this line, the “OX-ZEO” process that combines a methanol synthesis catalyst with a zeolite, capable of catalyzing the methanol-to-hydrocarbon reaction, was found to be a suitable alternative to the classical Fischer–Tropsch synthesis. Hitherto, understanding the mechanism of the OX-ZEO process and simultaneously optimizing the CO conversion and the selectivity toward a specific hydrocarbon remains challenging. Herein, we present a comparison of a variety of ZnCrAl oxides with different metal ratios combined with a H-ZSM-5 zeolite for the conversion of syngas to hydrocarbons. The effect of aluminum on the catalytic activity was investigated for ZnCrAl oxides with a Zn/Cr ratio of 4:1, 1:1, and 1:2. The product distribution and CO conversion were found to be strongly influenced by the Zn/Cr/Al ratio. Although a ratio of Zn/Cr of 1:2 was best to produce lower olefins and aromatics, with aromatic selectivities of up to 37%, catalysts with a 4:1 ratio revealed high paraffin selectivity up to 52%. Notably, a distinct effect of aluminum in the oxide lattice on the catalytic activity and product selectivity was observed, as a higher Al content leads to a lower CO conversion and a changed product spectrum. We provide additional understanding of the influence of different compositions of ZnCrAl oxides on their surface properties and the catalytic activity in the OX-ZEO process. Furthermore, the variation of the zeolite component supports the important role of the channel topology of the porous support material for the hydrocarbon production. In addition, variation of the gas hourly space velocity showed a correlation of contact time, CO conversion, and hydrocarbon selectivity. At a gas hourly space velocity of 4200 mL/gcat h, CO conversion as high as 44% along with a CO2 selectivity of 42% and a lower paraffin (C2 0–C4 0) selectivity of 41% was observed.

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Section: Resultsmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Influence of the ZnCrAl Oxide Composition on the Formation of Hydrocarbons from Syngas

et al. 2022

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“…The MeOH can be produced over an industrially applicable Cu/Zn/Al catalyst which is then converted to hydrocarbons over solid acids such as zeolites. However, recent progress in the route converts syngas to hydrocarbons in single-step catalysis, using oxygenated compounds such as MeOH, EtOH, formic acid, etc., as intermediates. , The insights into the different influences of the zeolite topology and acidity can correlate to identify the status quo for future references in catalyst fabrication. Here in this section, we highlight the major characteristics of zeolites that enhance the distinct production of valued products via syngas conversion.…”

Section: Sources Of Syngasmentioning

confidence: 99%

Tandem Reactions over Zeolite-Based Catalysts in Syngas Conversion

et al. 2022

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Syngas conversion can play a vital role in providing energy and chemical supplies while meeting environmental requirements as the world gradually shifts toward a net-zero. While prospects of this process cannot be doubted, there is a lingering challenge in distinct product selectivity over the bulk transitional metal catalysts. To advance research in this respect, composite catalysts comprising traditional metal catalysts and zeolites have been deployed to distinct product selectivity while suppressing side reactions. Zeolites are common but highly efficient materials used in the chemical industry for hydroprocessing. Combining the advantages of zeolites and some transition metal catalysts has promoted the catalytic production of various hydrocarbons (e.g., light olefins, aromatics, and liquid fuels) and oxygenates (e.g., methanol, dimethyl ether, formic acid, and higher alcohols) from syngas. In this outlook, a thorough revelation on recent progress in syngas conversion to various products over metal-zeolite composite catalysts is validated. The strategies adopted to couple the metal species and zeolite material into a composite as well as the consequential morphologies for specific product selectivity are highlighted. The key zeolite descriptors that influence catalytic performance, such as framework topologies, proximity and confinement effects, acidities and cations, pore systems, and particle sizes are discussed to provide a deep understanding of the significance of zeolites in syngas conversion. Finally, an outlook regarding challenges and opportunities for syngas conversion using zeolite-based catalysts to meet emerging energy and environmental demands is also presented.

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“…To improve further the catalytic performance, a variety of metal oxides have been screened, including single metal component oxides such as ZnO, MnO, Ga 2 O 3 , and CeO 2 , bimetal oxides such as ZnCrO x , ZnAlO x , ZnGaO x , ZnZrO x , ZnMnO x , CeZrO x, and even multimetal oxides. They were combined with various zeolites (zeotypes) such as SAPO-34, SAPO-18, MOR, and SSZ-13 for syngas conversion to light olefins . Among them, zinc–chromium based oxides were demonstrated to be one of the most active oxides so far. , …”

Section: Introductionmentioning

confidence: 99%

Visualization of the Active Sites of Zinc–Chromium Oxides and the CO/H₂ Activation Mechanism in Direct Syngas Conversion

Chen,

Han,

Pan

et al. 2024

J. Am. Chem. Soc.

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Despite wide studies demonstrating the versatility of the metal oxide-zeolite (OXZEO) catalyst concept to tackle the selectivity challenge in syngas chemistry, the active sites of metal oxides and the mechanism of CO/H 2 activation remain to be elucidated. Herein, we demonstrate experimentally the role of Cr in zinc−chromium oxides and unveil visually, for the first time, the active sites for CO activation employing scanning transmission electron microscopy-electron energy loss spectroscopy using the volumetric density of surface carbon species as a descriptor. The ZnCr 2 O 4 spinel surface with atomic ZnO x overlayer is the most active site for C−O bond dissociation, particularly at the narrow ZnCr 2 O 4 (110) facets constrained between the (311) and (111) facets, followed by the Cr-doped wurtzite ZnO surface. In comparison, the surfaces of ZnCr 2 O 4 with aggregated ZnO x overlayers, pure ZnO, and the stoichiometric ZnCr 2 O 4 exhibit a significantly lower activity. In situ synchrotron-based vacuum ultraviolet photoionization mass spectrometric study on different temperature programmed surface reactions with isotopes of C 18 O, 13 CO, and D 2 validates direct CO dissociation over ZnCr n oxides in CO, forming CH 2 and further to hydrocarbons if H 2 is present and CH 2 CO intermediates in syngas. The activity of CO dissociation and hydrogenation over ZnCr n oxides correlates well with the syngas-tolight-olefins activity of ZnCr n -SAPO-18 composite catalysts as a function of the Cr/Zn ratio.

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Direct Conversion of Syngas to Light Olefins over a ZnCrO_x + H-SSZ-13 Bifunctional Catalyst

Cited by 14 publications

References 38 publications

Influence of the ZnCrAl Oxide Composition on the Formation of Hydrocarbons from Syngas

Influence of the ZnCrAl Oxide Composition on the Formation of Hydrocarbons from Syngas

Tandem Reactions over Zeolite-Based Catalysts in Syngas Conversion

Visualization of the Active Sites of Zinc–Chromium Oxides and the CO/H₂ Activation Mechanism in Direct Syngas Conversion

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Direct Conversion of Syngas to Light Olefins over a ZnCrOx + H-SSZ-13 Bifunctional Catalyst

Cited by 14 publications

References 38 publications

Influence of the ZnCrAl Oxide Composition on the Formation of Hydrocarbons from Syngas

Influence of the ZnCrAl Oxide Composition on the Formation of Hydrocarbons from Syngas

Tandem Reactions over Zeolite-Based Catalysts in Syngas Conversion

Visualization of the Active Sites of Zinc–Chromium Oxides and the CO/H2 Activation Mechanism in Direct Syngas Conversion

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Product

Resources

About

Direct Conversion of Syngas to Light Olefins over a ZnCrO_x + H-SSZ-13 Bifunctional Catalyst

Visualization of the Active Sites of Zinc–Chromium Oxides and the CO/H₂ Activation Mechanism in Direct Syngas Conversion