Thesis Advisor李春山
Degree Grantor中国科学院大学
Degree Name博士
Degree Discipline化学工程

一步羟醛缩合法制备丙烯酸及其衍生物因其所用原料成本和能耗较其它工艺路线低而引起了研究者的兴趣。本文研究了一种新型乙酸乙酯和甲醛一步合成丙烯酸乙酯的新工艺。通过新型催化剂的设计、合成、反应器放大等研究,确定了催化剂的构效关系,具体研究结果如下。本文以γ-Al2O3为载体,开发了酸碱双功能催化剂Cs-P/γ-Al2O3,催化剂的活性用固定床反应器评价,反应温度为250℃-400℃,反应压力为常压。通过调控Cs-P/γ-Al2O3催化剂的酸碱性来优化催化活性,同时对反应条件如物料比、负载量和反应温度进行了优化。最优的条件为酯醛比为5:1,Cs和磷的负载量分别为10 %和3 %,反应温度为350℃,此时丙烯酸乙酯的收率为25.1%。通过引入镧系(La和Ce)和过渡金属(Y, Zr, Nb和W)等助剂显著提高了催化剂的活性。制得的催化剂采用X-射线晶体衍射(XRD),X-射线电子能谱(XPS),扫描电镜-色散谱(SEM-EDS),电子透射电镜(TEM),程序升温脱附(TPD),傅里叶红外(FT-IR),N2吸附-脱附(BET),热重分析(TGA)表征,获得了催化剂性能与结构的关系。研究结果表明,在10%-3%-Cs-P/γ-Al2O3催化剂中引入镧系和过渡金属助剂,Cs-P/γ-Al2O3的催化活性明显提高。Zr-Cs-P/γ-Al2O3催化剂对乙酸甲酯和甲醛的缩合反应活性最高,产物丙烯酸甲酯和丙烯酸的总收率为53.5 %,选择性为57.2 %;W-Cs-P/γ-Al2O3对乙酸乙酯和甲醛的缩合反应活性最好,产物丙烯酸乙酯的收率为41.2 %,选择性为59.8 %。通过表征发现,助剂能够有效调控催化剂表面的酸碱性,使其具有较好的催化活性。并考察了Zr-Cs-P/γ-Al2O3和W-Cs-P/γ-Al2O3催化剂的稳定性,反应60 h后产物收率下降60 %左右,其原因是催化剂表面形成了积碳,基于催化剂的活性寿命和失活原因,提出移动床新工艺。采用放大工艺制备所得的Cs-P/γ-Al2O3催化剂用于乙酸乙酯和甲醛制备丙烯酸乙酯的移动床放大实验(催化剂装填量为5 L)。结果表明当反应温度为350℃,LHSV为0.441 mL g-1 h-1时,丙烯酸乙酯的收率和选择性分别为9.5 %和32.2 %。;One step aldol condensation is an interesting route for the synthesis of acrylic acid and its derivative. Raw materials for this reaction are cheaper and energy consumption which uses in this system is lower than other routes. Several papers have been published on the reaction between the propionic acid (PA), methyl propionate (MP) or methyl acetate (MeOAc) with formaldehyde (FA) over a solid catalyst, while the reports on the reaction between ethyl acetate (EtOAc) and formaldehyde are unavailable. Herein, this work presents highly effective catalyst which can be prepared through simple preparation procedure and can be manufactured on a commercial scale for aldol condensation of ethyl acetate with formaldehyde.This thesis summarizes the method for catalyst preparation, catalyst characterization, aldol condensation activity in different types of reactor and reaction parameter, and correlation of catalyst properties and synthesis condition to their catalytic activities.This research explores the use of commercial γ-Al2O3 as support due to it is easy to apply on the commercial scale. Cesium and phosphorus were chosen as an active phase which exhibited basic and acid properties, respectively. Further, lanthanum metal (La, and Ce) and transition metal (Y, Zr, Nb, W) were investigated as a promoter to enhance the catalytic activity. All catalysts were characterized with different techniques such as X-ray diffraction (XRD), X-ray photoelectron (XPS), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), transmission electron microscopy (TEM), temperature program desorption (TPD), Fourier transform infrared (FT-IR), N2 adsorption-desorption, and thermogravimetric analysis (TGA). The aldol condensation of ethyl acetate with formaldehyde activities was performed in a tubular fixed-bed reactor under atmospheric pressure at the temperature between 250°C to 400°C.Phosphorus-cesium over alumina (P-Cs/γ-Al2O3) catalysts were developed with highly improved catalytic performance with the influence of acidity and basicity. Key reaction parameters, such as reactant ratio, the amount of metal loading, reaction temperature, were optimized. The optimum condition was EtOAc:FA of 5:1 with 3%-10% P-Cs/γ-Al2O3 at 350°C, which demonstrated a maximum yield of 25.1%.Further, 3%-10% P-Cs/γ-Al2O3 catalyst was modified with different metals and employed for the reaction of acetic acid ester (MeOAc and EtOAc) with formaldehyde. The Zr-P-Cs/γ-Al2O3 catalyst exhibited maximum yield (53.5 %) and selectivity (57.2 %) of methyl acrylate (MA) + acrylic acid (AA). The W-P-Cs/γ-Al2O3 catalyst showed good performance on production of ethyl acrylate (EA), with the yield of 41.2 % and selectivity of 59.8 %. The addition of small amount of metal improved the catalytic performance as compared to P-Cs/γ-Al2O3 catalyst. Thus, the addition of metal influenced the acidity and basicity of the surface of the catalyst and exhibited significantly enhanced aldol condensation activity. Moreover, the stability of Zr-P-Cs/γ-Al2O3 and W-P-Cs/γ-Al2O3 catalysts were tested. Yields declined by nearly 60% after reaction at 60 h, due to the formation of carbon deposition on the surface of the catalyst. Moreover, the scale up of the aldol condensation of ethyl acetate with formaldehyde was performed in the moving-bed reactor with 5 L of P-Cs/γ-Al2O3 catalyst. The best catalytic activity was exhibited under reaction temperature at 350 °C with LHSV of 0.441 mL g-1 h-1, which was produced 9.53% of EA yield and 32.2% of EA selectivity.

Document Type学位论文
Recommended Citation
GB/T 7714
CHIDCHON SARARUK. 改性Cs/γ-Al2O3催化乙酸乙酯和甲醛羟醛缩合制备[D]. 中国科学院大学,2017.
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改性Cs_γ-Al2O3催化乙酸乙酯和甲(5408KB)学位论文 限制开放CC BY-NC-SAApplication Full Text
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