磺酸树脂催化甲缩醛一步羰化制高附加值甲氧基乙酸甲酯

摘要

甲氧基乙酸甲酯(MMAc)是重要的精细化学品,同时是拟开辟的由合成气间接法制乙二醇的中间产物.鉴于文献报道的甲缩醛(DMM)气相羰化制MMAc存在CO与DMM比例过高(>100),CO一次转化率过低(<0.5%)等缺点,采用釜式反应器,系统研究液相DMM羰基化反应过程中诸多因素,如溶剂种类、不同牌号磺酸树脂催化剂、反应温度、压力、反应时间、催化剂前处理等因素对DMM转化率以及产物MMAc选择性的影响.环丁砜显著提高了CO在液相中的溶解度,并有效抑制醛基游离以及DMM歧化反应,使DMM最大限度地向羰化反应方向进行.采用H-Y分子筛为催化剂,在反应温度120℃,初始反应压力3.0 MPa时,MMAc选择性仅为5%,而以磺酸树脂为催化剂时,MMAc选择性可以达到45%,说明磺酸树脂催化剂比H-Y分子筛具有更强的羰化能力.DMM在H-Y分子筛微孔表面更易发生歧化反应,导致二甲醚选择性大于90%.DMM转化率随反应温度、压力的增高和反应时间的增长而增大,MMAc选择性随反应时间增长和压力增高而提高、随着反应温度的升高先提高后降低.随着催化剂前处理温度升高,树脂催化剂中吸附的水含量逐渐减少,MMAc选择性逐步提高,但过高温度会导致催化剂孔道塌陷、表面结焦,羰化效果变差.以环丁砜为溶剂,D-009B树脂为催化剂,反应温度110℃、压力5 MPa、反应6 h,DMM转化率接近100%,MMAc选择性达到74.32%,显示较好的工业应用前景.%Methyl methoxyacetate (MMAc), an important fine chemical, is an intermediate product producing ethylene glycol from syngas. Literature reports showed that high molar ratio of CO to DMM (>100) and low CO conversions (<0.5%) were obviously beneficial for vapor-phase carbonylation of dimethoxymethane (DMM) to MMAc. Using a slurry phase reactor, this work systematically studied the effects of different solvents, sulfonic acid resin catalysts, reaction temperature, pressure, reaction time and drying temperature on DMM conversion and MMAc selectivity. The solubility of CO in liquid phase was significantly increased by sulfolane solvent , thus obviously promoting the carbonylation reaction and suppressing the hydration as well as disproportionation reactions of DMM. Comparing with H-Y, the carbonylation activity of sulfonic acid resin catalyst was higher. The high rate of DMM disproportionation for H-Y was attributed to the micropores of zeolite, which facilitated a critical initial step in the formation of DME and MF. With the increased reaction temperature, pressure or reaction time, the conversion of DMM increases, whereas the selectivity of MMAc first increased and then decreased. With increasing the drying temperature, the moisture content left in the resin gradually decreased. But higher drying temperature resulted in the collapse of pores and surface sintering. For the liquid phase carbonylation process, many complicated and unreported side reactions were accompanied. The DMM conversion can reach to about 100% with 74.32% MMAc selectivity using sulfolane as solvent and D-009B as the catalyst at 110℃ and 5 MPa for 6 h. It was anticipated that this direct carbonylation of DMM to produce MMAc process was promising for industrial manufacture.