【摘要】 以硅胶、氧化镁、椰壳活性炭和活性氧化铝为载体、以KOH为活性组分制得一系列新型负载型固体碱催化剂。考察了催化剂对超临界CO2和CH3OH直接合成碳酸二甲酯反应的催化性能。结果表明:以椰壳活性炭为载体的KOH负载型催化剂的催化活性最高。采用比表面积测试(BET)、X-射线衍射(XRD)和扫描电镜(SEM)表征等手段对催化剂进行结构测试表明:椰壳活性炭的比表面积最大,能够很好地作为载体;负载的KOH经高温焙烧后分解为K2O,提高了催化剂活化CO2的能力;负载后的催化剂表面晶型孔道尺寸变大,K2O在催化剂的表面及孔道内壁上分散较好。以KOH/C为催化剂,重点考察了KOH负载量、不同催化体系、反应温度和压力等对催化剂活性的影响;最后对反应过程进行了强化,获得了最佳条件下合成DMC的产率为8.5%,优于现有超临界非均相催化直接合成DMC的文献报道结果。更多还原

【Abstract】 A series of solid base catalysts were prepared for the direct synthesis of dimethyl carbonate(DMC) using CO2 and CH3 OH. These catalysts were prepared via an iso-volumic impregnation method using KOH as an active component which was supported by silica gel, magnesium oxide, activated carbon and alumina respectively. The experimental results show that the catalytic activity of the activated carbon supported KOH has the best performance. The catalysts were characterized by Brunauer-Emmett-Teller(BET), X-ray diffraction(XRD) and scanning electron microscope(SEM), and the experimental results show that the activated carbon with large specific surface area tends to be a good carrier. After high temperature calcination, KOH decomposes into K2 O crystal which improves its catalytic activation. K2 O disperses well on the surface and inner wall of the carriers. The effects of KOH loading amount, additive composition, reaction temperature and pressure were investigated and the reaction process was optimized. The yield of DMC is 8.5% under the optimum conditions, which is superior to the existing results of supercritical heterogeneous catalysis of DMC synthesis reported in the literature.更多还原