Effect of surface defects density of carbon spheres on the catalytic performance of the supported Cu catalyst for oxidativecarbonylation of methanol

doi:10.16085/j.issn.1000-6613.2018-2121

Abstract

Abstract:

A series of ordered microporous carbon spheres (CS) with different surface defect density were prepared by hydrothermal polymerization method, then the CS surface-supported Cu catalysts were prepared and evaluated for methanol oxidative carbonylation to synthesize dimethyl carbonate. From the characterization results , the influence of surface defect density of CS on the structure and the catalytic performance of Cu/CS were studied. The results indicated that the surface defect density of CS increase with the increase of its particle size, and the dispersion of Cu species became better with the increase of surface defect density. Moreover, the increased surface defect density was conducive to the enhanced interaction between CS and Cu species, and to the auto-reduction of CuO to active species Cu₂O and Cu, and thus improved the catalytic activity. The long-term evaluation results suggested that the oxidation and agglomeration of Cu species resulted in the deactivation of Cu/CS catalysts. The surface defect of CS inhibited the oxidation of active Cu species in the reaction process. The higher surface defect density, the stronger the antioxidant capacity of Cu species. However, the Cu species with small particle size induced by high surface defect density aggregated easily in the reaction process due to their high surface energy.

Key words: catalyst, ordered microporous carbon spheres, dimethyl carbonate, oxidative carbonylation, defect density

摘要：

采用水热聚合法合成了一系列表面缺陷密度不同的有序微孔碳球（CS），并以其为载体制备了表面负载铜催化剂（Cu/CS），用于催化气相甲醇氧化羰基化合成碳酸二甲酯。结合表征结果，研究了载体表面缺陷密度对Cu/CS催化剂结构及催化性能的影响。结果表明，CS的表面缺陷密度随其粒径增大而增大，且其缺陷密度越大，催化剂中Cu物种分散度越高；同时，较大的表面缺陷密度有利于增强载体与Cu物种间的相互作用力，促进CuO自还原为活性物种Cu₂O和Cu，从而提高催化活性。长期评价结果表明，Cu物种的氧化和团聚是造成Cu/CS催化剂失活的原因。CS的表面缺陷抑制了反应过程中活性Cu物种的氧化，且缺陷密度越大，Cu物种抗氧化能力越强；但表面缺陷密度大的催化剂中Cu物种颗粒尺寸小，表面能高，因而更容易发生团聚。

关键词: 催化剂, 有序微孔碳球, 碳酸二甲酯, 氧化羰基化, 缺陷密度

CLC Number:

O643

Dongsen JIA,Guoqiang ZHANG,Jiao YIN,Liangliang ZHANG,Dan ZHAO,Huayan ZHENG,Zhong LI. Effect of surface defects density of carbon spheres on the catalytic performance of the supported Cu catalyst for oxidativecarbonylation of methanol[J]. Chemical Industry and Engineering Progress, 2019, 38(08): 3701-3710.

贾东森,张国强,尹娇,张亮亮,赵丹,郑华艳,李忠. 碳球表面缺陷密度对其负载铜催化剂甲醇氧化羰基化反应性能的影响[J]. 化工进展, 2019, 38(08): 3701-3710.

Figures/Tables 12

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样品	比表面积/m²·g^-1		孔体积/m³·g^-1		最可几孔径^③/nm
样品	总比表面积	微孔比表面积^①	总孔体积	微孔体积^②	最可几孔径^③/nm
CS-1	613	525	0.61	0.50	1.84
CS-2	600	505	0.62	0.51	1.86
CS-3	626	523	0.64	0.53	1.85
Cu/CS-1	588	495	0.59	0.49	1.84
Cu/CS-2	590	491	0.61	0.50	1.86
Cu/CS-3	617	509	0.62	0.51	1.85

样品	比表面积/m²·g^-1		孔体积/m³·g^-1		最可几孔径^③/nm
样品	总比表面积	微孔比表面积^①	总孔体积	微孔体积^②	最可几孔径^③/nm
CS-1	613	525	0.61	0.50	1.84
CS-2	600	505	0.62	0.51	1.86
CS-3	626	523	0.64	0.53	1.85
Cu/CS-1	588	495	0.59	0.49	1.84
Cu/CS-2	590	491	0.61	0.50	1.86
Cu/CS-3	617	509	0.62	0.51	1.85

催化剂	W _Cu/%	d _Cu ^①/nm	S _Cu ^②/m²·g^-1	D _Cu ^③/%	C _CH3OH/%	S _DMC/%	STY_DMC /mg·g^-1·h^-1
Cu/CS-1	10	3.6	42.9	63.2	3.4	70.0	276.6
Cu/CS-2	10	4.2	37.0	54.6	2.4	71.3	199.2
Cu/CS-3	10	4.9	27.3	40.3	2.0	69.5	161.1
Cu/AC^[30]	12	32.0	—	—	6.0	62.1	156.0
Cu/SCS^[11]	10	9.9	—	—	0.7	52.7	47.4

催化剂	W _Cu/%	d _Cu ^①/nm	S _Cu ^②/m²·g^-1	D _Cu ^③/%	C _CH3OH/%	S _DMC/%	STY_DMC /mg·g^-1·h^-1
Cu/CS-1	10	3.6	42.9	63.2	3.4	70.0	276.6
Cu/CS-2	10	4.2	37.0	54.6	2.4	71.3	199.2
Cu/CS-3	10	4.9	27.3	40.3	2.0	69.5	161.1
Cu/AC^[30]	12	32.0	—	—	6.0	62.1	156.0
Cu/SCS^[11]	10	9.9	—	—	0.7	52.7	47.4

催化剂	Cu2p_3/2结合能/eV		表面Cu物种的摩尔分数/%
催化剂	Cu²⁺	Cu⁺+Cu⁰	Cu²⁺	Cu⁺+Cu⁰
Cu/CS-1	934.7	933.3	54.3	45.7
Cu/CS-2	934.8	933.4	56.3	43.7
Cu/CS-3	934.7	933.2	62.4	37.6
反应后Cu/CS-1	934.9	933.1	57.0	43.0
反应后Cu/CS-2	934.8	933.1	60.8	39.2
反应后Cu/CS-3	935.7	933.5	80.3	19.7