Spacial hindrance induced recovery of over-poisoned active acid sites in pyridine-modified H-mordenite for dimethyl ether carbonylation

Zhao, Na; Tian, Ye; Zhang, Lifu; Cheng, Qingpeng; Lyu, Shuaishuai; Ding, Tao; Hu, Zhenpeng; Ma, Xinbin; Li, Xingang

doi:10.1016/s1872-2067(19)63335-8

Cited by 25 publications

(14 citation statements)

References 47 publications

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“…Mordenite (MOR) and ferrierite (FER) zeolites have been demonstrated to be the most efficient catalysts for DME carbonylation. − In particular, MOR exhibits the highest carbonylation activity and selectivity to the desired product MA. An MOR framework consists of a parallel 12-membered ring (12-MR, 6.5 × 7.0 Å 2 ) and 8-MR channels (2.6 × 5.7 Å 2 ) along the c axis direction, both of which are interconnected by 8-MR side pockets (3.4 × 4.8 Å 2 ) along the b axis direction. , As the 8-MR channels along the c axis are too narrow for most molecules to penetrate, MOR practically behaves as a unidimensional zeolite in catalytic reactions.…”

Section: Introductionmentioning

confidence: 99%

Insights into the Pyridine-Modified MOR Zeolite Catalysts for DME Carbonylation

Cao

Fan

et al. 2020

ACS Catal.

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Pyridine-modified mordenite (MOR) zeolite catalysts have attracted great attention in recent years due to their unique shape selectivity within eight-membered ring (8-MR) side pockets for dimethyl ether (DME) carbonylation to methyl acetate (MA) and syngas conversion to ethylene. Herein, aimed at elucidating pyridine modification−carbonylation activity relationships and developing high-performance catalysts, we investigated the adsorption/desorption behaviors of pyridine on MOR zeolites with varying Si/Al ratios and their impact on DME carbonylation. Instead of the previously proposed selective adsorption of pyridine in 12-MR channels, pyridine is revealed to penetrate into 8-MR side pockets of MOR zeolites and interact with acidic hydroxyls therein. Upon heating, pyridine in pockets desorbs preferentially, likely arising from the lower stability of pyridine adspecies in constrained spaces. This well explains the observed increment of carbonylation activity following the increase of pretreatment temperature. Unprecedentedly, high MA yield (7.2 mmol/(h g)) has been achieved on pyridine-modified MOR (Si/Al = 13.8) under controlled pyridine desorption conditions, resulting from the joint contributions of better diffusion properties and larger amounts of active acid sites. Moreover, the catalytic activity of Brønsted acid sites within 8-MR pockets is demonstrated to be inhomogeneous, closely associated with their locations.

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Section: Introductionmentioning

confidence: 99%

Insights into the Pyridine-Modified MOR Zeolite Catalysts for DME Carbonylation

Cao

Fan

et al. 2020

ACS Catal.

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“…2 presents the UV-Vis spectrophotometric curve of the unmodified HMOR and the HMOR-Pya-1.3 sample. The absorption peak at 206 nm was attributed to HMOR, 14 and the absorption peak of HMOR modified with Pya·HCl appeared at 214 nm. The absorption peak of pyrazole in the near ultraviolet region of 200–400 nm was corresponded to the π → π* transition at 211 nm.…”

Section: Resultsmentioning

confidence: 99%

Enhancing the dimethyl ether carbonylation performance over hydrogen-type mordenites modified by pyrazole hydrochloride

et al. 2022

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“…Xue et al [21] used steam treatment for the selective dealumination of MOR, reducing the amount of acid sites in 12-MR. Zhao et al [22] formed more Brønsted acid sites in the MOR through steam treatment and improved the reaction activity. Moreover, acid treatment [23], alkali treatment [24], and pyridine adsorption [25][26][27] were also effective in improving the activity of the catalyst and alleviating catalyst poisoning.…”

Section: Introductionmentioning

confidence: 99%

Silver-Modified Nano Mordenite for Carbonylation of Dimethyl Ether

Qian

et al. 2021

Catalysts

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Mordenite (H-MOR) catalysts were synthesized by a hydrothermal method, and silver-modified mordenite (Ag-MOR) catalysts were prepared by ion exchange with AgNO3 at different concentrations. The performance of these catalysts in the carbonylation of dimethyl ether (DME) to methyl acetate (MA) was also evaluated. The catalysts were characterized by Ar adsorption/desorption, XRD, ICP-AES, SEM, HRTEM, 27Al NMR, H2-TPR, NH3-TPD, Py-IR, and CO-TPD. According to the characterization results, Ag ion exchange sites were mainly located in the 8-membered ring (8-MR) channels of Ag-MOR; evenly dispersed Ag2O particles were also present. The acid site distribution was changed by the modification of Ag, and the amount of Brønsted acid sites increased in 8-MR and decreased in 12-MR. The CO adsorption performance of the catalyst significantly increased with the modification of Ag. These changes improved the conversion and selectivity of the carbonylation of DME. Over 4Ag-MOR in particular, DME conversion and MA selectivity reached 94% and 100%, respectively.

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Spacial hindrance induced recovery of over-poisoned active acid sites in pyridine-modified H-mordenite for dimethyl ether carbonylation

Cited by 25 publications

References 47 publications

Insights into the Pyridine-Modified MOR Zeolite Catalysts for DME Carbonylation

Insights into the Pyridine-Modified MOR Zeolite Catalysts for DME Carbonylation

Enhancing the dimethyl ether carbonylation performance over hydrogen-type mordenites modified by pyrazole hydrochloride

Silver-Modified Nano Mordenite for Carbonylation of Dimethyl Ether

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