摘要
以具有酸性特性的HZSM-5分子筛为载体,结合金属本身具有的羰基化活性,可以更好的提高羰基化反应效率。采用负压沉积沉淀法对HZSM-5催化剂进行Pt、Pd、Cu、Au、Zn改性,制备不同酸度的催化剂。利用X射线衍射、NH3程序升温脱附、吡啶吸附FTIR、N;吸附-脱附和X射线荧光分析研究了不同金属对催化剂物理化学性质及不同负载型HZSM-5催化剂对甲醇羰基化产物的分布和产率的影响。结果表明,不同金属的引入对HZSM-5催化剂的比表面积、孔径和孔体积影响较小,但明显地改变了催化剂表面的酸强度。Pt、Au、Zn和Cu改性后的催化剂更有利于甲醇羰基化反应的进行,其中Cu/HZSM-5催化剂在400℃的甲醇转化率高达90.2%,比HZSM-5催化剂的甲醇转化率高12%,但目标产物的选择性比Pt/HZSM-5及Au/HZSM-5的低。总的来看,金属的引入改变了催化剂表面Br?nsted酸(B酸)和Lewis酸(L酸)中心的数量,甲醇的转化率随总酸量的增加而增加,催化剂表面B酸与L酸的比例在0.3~0.5时,催化剂表现出更好的羰基化作用。
In this study, selective production of methanol carbonylation formed acetic acid using hydrothermal synthesis nanoporous zeolite molecular sieve as the catalyst. The incorporation of a suitable amount of metal not only facilitated the formation of acidity but also improved the efficiency of methanol carbonylation. The HZSM-5catalyst was modified with Pt, Pd, Cu, Au, Zn by negative pressure deposition precipitation method to prepare catalysts with different acidities. Using X-ray diffraction, temperature-programmed desorption of ammonia, pyridine adsorption FTIR, N;adsorption-desorption, and X-ray fluorescence analysis, the effect of different metals on the physico-chemical properties of the catalyst was studied, and the modification of HZSM-5 with different metals was investigated in the process of methanol carbonylation on the distribution and yield of methanol carbonyl products.The introduction of different metals had little effect on the specific surface area, pore size, and pore volume of the HZSM-5 catalyst, but significantly changed the acid strength of the catalyst surface. Pt, Au, Zn, and Cu modified HZSM-5 were favorable for the carbonylation of methanol to form methyl acetate and methyl formate. Cu-modified catalyst had a methanol conversion rate of 90.2% at 400 ℃, which was 12% higher than that of pristine HZSM-5,but the selectivity to the target product was lower than those of Pt/HZSM-5 and Au/HZSM-5. In a word, the introduction of metals changes the number of Br?nsted acid(B acid) and Lewis acid(L acid) centers on the catalyst surface.The conversion rate of methanol increased with the total acid sites. When the ratio of B acid to L acid on the catalyst surface was between 0.3 and 0.5, the catalyst showed better carbonylation activity.
作者
迪丽努尔·艾力
高希然
毕坤豪
方亚平
樊星
艾沙·努拉洪
Dilinuer Aili;GAO Xi-Ran;BI Kun-Hao;FANG Ya-Ping;FAN Xing;Aisha Nulahong(State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources,School of Chemical Engineering and Technology,Xinjiang University,Urumqi 830017,China)
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2022年第5期901-912,共12页
Chinese Journal of Inorganic Chemistry
基金
新疆维吾尔自治区重点实验室开放课题(No.2017D04005)
国家自然科学基金(No.21563028)资助。
