Controlled preparation and performance regulation of catalysts for one-step synthesis of methyl propionate from methanol and methyl acetate

doi:10.11949/0438-1157.20250156

Abstract

Abstract:

Methyl propionate (MP), as a key organic intermediate in pharmaceutical and fragrance synthesis, currently faces production challenges including high energy consumption during separation and low production efficiency. Based on this, this study proposes a new route for continuous synthesis of MP in a fixed bed reactor using methanol and methyl acetate as raw materials under high partial pressure (60 kPa) of raw materials. A series of high-performance Ti-modified Cs/SiO₂ catalysts were developed, and their physicochemical properties were characterized using XRD, BET, TEM, XPS, CO₂/NH₃-TPD and UV-Vis spectroscopy. The results indicate that the introduction of Ti significantly modulates the acid-base properties of the catalyst, and the proportion of weak acid sites to total acid sites coupled with the ratio of weak base sites to total base sites critically governs the activity in aldol condensation reactions. In the key step of the one-step MP synthesis (aldol condensation of formaldehyde and methyl acetate), the conversion of methyl acetate exhibited a volcano-shaped trend with the loading of Ti, reaching a maximum of 29.4% at a Ti loading of 4%(mass). Correspondingly, in the tandem reaction of methanol and methyl acetate to produce MP, the catalyst demonstrated the highest catalytic activity, with an MP yield of 23.6%. This study elucidates the mechanism by which Ti modification affects the acid-base properties and reaction performance of the catalysts, providing theoretical insights and technical support for the catalyst design and process scale-up of one-step MP synthesis from methanol and methyl acetate.

Key words: aldol condensation, tandem catalysis, acid-base regulation, catalyst, methyl propionate, multiphase reaction, synthesis

摘要：

丙酸甲酯（MP）作为医药、香料合成等领域的关键有机中间体，其现有生产工艺面临分离能耗高、生产效率低等挑战。基于此，本研究提出一种以甲醇与乙酸甲酯为原料，在原料高分压（60 kPa）条件下在固定床反应器内连续合成MP的新路线。通过Ti改性策略构筑了一系列高性能Ti-Cs/SiO₂催化剂，并采用XRD、BET、TEM、XPS、CO₂/NH₃-TPD和UV-Vis测试对其物理化学特性进行了表征。结果表明，Ti的引入显著调节了催化剂的酸碱特性，弱酸占总酸位点与弱碱占总碱位点比例对羟醛缩合反应活性有重要影响。在一步法制MP的关键步骤（甲醛和乙酸甲酯羟醛缩合反应）中，乙酸甲酯的转化率随Ti的负载量呈火山型趋势变化，当Ti的负载量为4%（质量分数）时，转化率最高（29.4%）。相应地，在甲醇和乙酸甲酯一步法制MP的串联反应中，该催化剂表现出最高的催化活性，MP的收率达23.6%。本研究揭示了Ti改性对催化剂酸碱特性及反应性能的影响机制，为甲醇和乙酸甲酯一步法合成MP的催化剂设计及工艺放大提供了理论依据和技术支撑。

关键词: 羟醛缩合, 串联催化, 酸碱调控, 催化剂, 丙酸甲酯, 多相反应, 合成

CLC Number:

TQ 032.4

Xinyi CHAO, Wenyao CHEN, Jing ZHANG, Gang QIAN, Xinggui ZHOU, Xuezhi DUAN. Controlled preparation and performance regulation of catalysts for one-step synthesis of methyl propionate from methanol and methyl acetate[J]. CIESC Journal, 2025, 76(8): 4030-4041.

巢欣旖, 陈文尧, 张晶, 钱刚, 周兴贵, 段学志. 甲醇和乙酸甲酯一步法制丙酸甲酯催化剂的可控制备与性能调控[J]. 化工学报, 2025, 76(8): 4030-4041.

Figures/Tables 11

Fig.1 Schematic diagram of the catalyst performance evaluation apparatus and process

Fig.2 Elemental distribution and morphological analysis of the catalysts

Fig.3 N2 adsorption-desorption isotherms and pore size distribution curves of the support and supported catalysts

Table 1 Pore structure parameters of the support and supported catalysts

催化剂	比表面积/(m²/g)	孔容/(cm³/g)	平均孔径/nm
SiO₂	428.9	0.76	6.71
Cs/SiO₂	92.0	0.59	21.85
1Ti-Cs/SiO₂	235.9	0.84	11.48
2Ti-Cs/SiO₂	240.9	0.75	9.65
3Ti-Cs/SiO₂	241.5	0.65	8.62
4Ti-Cs/SiO₂	246.1	0.64	8.42
5Ti-Cs/SiO₂	269.3	0.70	8.19

Fig.4 XPS spectra of catalysts

Table 2 Ratios of Ti3+， Ti4+ and Olatt in the catalysts

催化剂	Ti³⁺/Ti	Ti⁴⁺/Ti	O^latt/O
Cs/SiO₂	—	—	14.2%
1Ti-Cs/SiO₂	32.18%	67.82%	14.4%
2Ti-Cs/SiO₂	36.60%	63.40%	16.4%
3Ti-Cs/SiO₂	40.78%	59.22%	17.0%
4Ti-Cs/SiO₂	47.06%	52.94%	17.3%
5Ti-Cs/SiO₂	50.52%	49.48%	17.6%

Fig.5 UV-Vis absorption spectra of xTi-Cs/SiO₂ catalysts

Fig.6 NH₃-TPD and CO₂-TPD profiles of the catalysts

Table 3 Acid-base properties of catalysts

催化剂	总酸量/ (μmol/g)	不同强度酸量/(μmol/g)			总碱量/ (μmol/g)	不同强度碱量/(μmol/g)
催化剂	总酸量/ (μmol/g)	弱	中强	强	总碱量/ (μmol/g)	弱	中强	强
1Ti-Cs/SiO₂	87	36	37	15	188	90	60	36
2Ti-Cs/SiO₂	101	43	40	17	164	84	59	22
3Ti-Cs/SiO₂	115	52	48	15	142	77	47	19
4Ti-Cs/SiO₂	130	64	51	16	123	73	37	13
5Ti-Cs/SiO₂	134	72	51	11	110	72	35	3

Fig.7 Catalytic performance of xTi-Cs/SiO2 catalysts in fixed-bed reactor and correlation between weak acid/base site proportion and aldol condensation performance

Fig.8 Cyclic stability and regenerability of 4Ti-Cs/SiO2 catalyst in one-step synthesis of MP from methanol/methyl acetate

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