中文摘要：

二甲醚（DME）羰基化制乙酸甲酯（MA）及MA加氢制乙醇,是一条新兴的合成气间接法制乙醇工艺.其中,DME羰基化合成MA反应原子经济性高,反应条件温和.特别是以丝光沸石（MOR）为催化剂时,反应在较低温度（473K）下MA选择性即可达到99%,这使得该工艺具有良好的竞争力和工业化前景.在已有的文献报道中,学者们将MA的高选择性归结于分子筛八元环（8-MR）结构的限域效应,红外和DFT计算表明八元环的Bronsted酸位上可以专一性催化CO插入吸附态的甲基形成乙酰基中间体.为了建立八元环Bronsted酸位点与活性的关系,研究者一般采用化学脱铝和离子交换等方法减少八元环Bronsted酸位点,以观察反应活性降低的趋势.事实上,采用直接合成手段选择性地调控H-MOR的酸性,以此提高其羰基化活性的研究报道十分有限.因此,我们通过多种方法来调变MOR的骨架Al元素分布,包括改变水热合成中溶胶的组成、选择适宜的模板剂以及对样品进行酸处理等,获得了一系列酸量和酸分布不同的H-MOR分子筛.通过考察DME羰基化制MA的反应性能,进一步明确酸性调控对分子筛催化剂结构和性能的影响.首先通过XRD和N2物理吸附对所有样品的织构性质进行表征,结果发现各样品均为纯的MOR晶相,相对结晶度也较为相近.比表面积和孔分布计算结果显示,各样品的孔结构也大致相同.特殊地,以环己亚胺（HMI）为模板时得到的样品结晶度较低,比表面积和孔体积较小.这是因为HMI的碱性较弱,因此在水热合成过程中的结构导向力较弱,无法高效地促进分子筛成核.酸处理会造成分子筛骨架T原子少量脱除,导致结构轻微破坏,但总的来说影响不大.在排除了晶相与结构方面的差异后,我们基于不同环内酸性位点对不同尺寸碱性分子的可接近性存在差异这一特点,结合ICP-OES,27Al MAS NMR,NH3-TPD和Py-FTIR等多种表征方法对MO

英文摘要：

Among the reactions catalyzed by zeolites there are some that exhibit high selectivity due to the spatial confinement effect of the zeolite framework.Tailoring the acidity,particularly the distribution and location of the Bronsted acid sites in the zeolite is effective for making it a better catalyst for these reactions.We prepared a series of H-mordenite（H-MOR） samples by varying the composition of the sol-gel,using different structure directing agents and post-treatment.NH3-TPD and IR characterization of adsorbed pyridine were employed to determine the amount of Bronsted acid sites in the 8-membered ring and 12-membered ring channels.It was shown that controlled synthesis was a promising approach to improve the concentration of Bronsted acid sites in MOR,even with a low Al content.Using an appropriate composition of Si and Al in the sol-gel favored a higher proportion of Bronsted acid sites in the 8-membered ring channels.HMI as a structure-direct agent gave an obvious enrichment of Bronsted acid sites in the 8-membered ring.Carbonylation of dimethyl ether was used as a probe reaction to examine the modification of the acid properties,especially the Bronsted acid sites in the 8-membered ring channels.There was a linear relationship between methyl acetate formation and the number of Bronsted acid sites in the 8-membered ring channels,demonstrating the successful modification of acid properties.Our results provide information for the rational design and modification of zeolites with spatial constraints.