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Study of the Nature of High-Silica H–Y Acid Sites in Dimethoxymethane Carbonylation by NH3 Poisoning
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2018-04-19 00:00:00 , DOI: 10.1021/acs.jpcc.8b00421 Zhiqiang Xie 1, 2 , Congbiao Chen 1 , Bo Hou 1 , Dekui Sun 1 , Heqin Guo 1 , Jungang Wang 1 , Debao Li 1 , Litao Jia 1
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2018-04-19 00:00:00 , DOI: 10.1021/acs.jpcc.8b00421 Zhiqiang Xie 1, 2 , Congbiao Chen 1 , Bo Hou 1 , Dekui Sun 1 , Heqin Guo 1 , Jungang Wang 1 , Debao Li 1 , Litao Jia 1
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The nature of high-silica H–Y acid sites in dimethoxymethane carbonylation is investigated by NH3 poisoning with a combination of reaction results, diffuse reflection infrared Fourier transform spectra, and NH3 temperature-programmed desorption. After NH3 poisoning of H–Y, ammonia desorption of zeolites NH4–Y was conducted at different temperatures to obtain catalysts HNH4–Y that gradually exposed different acid sites. The zeolites thus produced catalyzed dimethoxymethane carbonylation with a linear dependence of the conversion on the ammonia desorption temperature before the plateau stage. It was observed that strong Brønsted acids in zeolite Y catalyzed the reaction more selectively toward the main product methyl methoxyacetate, and weak Brønsted acids catalyzed the reaction more selectively toward the byproduct methyl formate. Furthermore, the turnover frequency of Brønsted acids varied significantly among the Brønsted acids and decreased with acid strength. This finding suggested that only 10.1–18.3% of the total Al in zeolite Y with Si/Al ratios of 15, 30, and 40 contributed to the total framework Brønsted acids.
中文翻译：
NH 3中毒二甲氧基甲烷羰基化反应中高硅酸H-Y酸位的性质研究
NH 3中毒结合反应结果，漫反射红外傅里叶变换光谱和NH 3程序升温脱附，研究了二甲氧基甲烷羰基化反应中高硅酸H-Y酸位的性质。NH 3中毒后，在不同温度下进行NH 4 -Y沸石的氨解吸，得到催化剂HNH 4–Y逐渐暴露出不同的酸位。如此产生的沸石催化了二甲氧基甲烷羰基化，转化率与平稳阶段之前的氨解吸温度呈线性关系。观察到，沸石Y中的强布朗斯台德酸对主产物甲氧基乙酸甲酯更选择性地催化反应，而弱布朗斯台德酸对副产物甲酸甲酯更选择性地催化反应。此外，布朗斯台德酸的周转频率在布朗斯台德酸之间显着变化，并且随着酸强度而降低。这一发现表明，沸石Y / Si / Al比为15、30和40的沸石中，总Al中只有Al的10.1–18.3％构成了布朗斯台德酸的总骨架。
更新日期：2018-04-19
中文翻译：
NH 3中毒二甲氧基甲烷羰基化反应中高硅酸H-Y酸位的性质研究
NH 3中毒结合反应结果，漫反射红外傅里叶变换光谱和NH 3程序升温脱附，研究了二甲氧基甲烷羰基化反应中高硅酸H-Y酸位的性质。NH 3中毒后，在不同温度下进行NH 4 -Y沸石的氨解吸，得到催化剂HNH 4–Y逐渐暴露出不同的酸位。如此产生的沸石催化了二甲氧基甲烷羰基化，转化率与平稳阶段之前的氨解吸温度呈线性关系。观察到，沸石Y中的强布朗斯台德酸对主产物甲氧基乙酸甲酯更选择性地催化反应，而弱布朗斯台德酸对副产物甲酸甲酯更选择性地催化反应。此外，布朗斯台德酸的周转频率在布朗斯台德酸之间显着变化，并且随着酸强度而降低。这一发现表明，沸石Y / Si / Al比为15、30和40的沸石中，总Al中只有Al的10.1–18.3％构成了布朗斯台德酸的总骨架。
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