Abstract A series of Ti(SO4)2/activated carbon spheres (CS) bifunctional catalysts were designed and prepared by impregnation method, and the effect of calcination temperature of the catalysts on direct oxidation of dimethyl ether (DME)to polyoxymethylene dimethyl ethers (DMMx) was investigated. The results showed that the performance of Ti(SO4)2/CS catalysts was closely related to the calcination temperature. The 30%Ti(SO4)2/CS catalyst calcined under O2 atmosphere at 280°Cexhibited excellent activity over which the conversion of DME reached 11.7% with the selectivity of DMM1-3 up to 75.8%,wherein, the selectivity of DMM2,3 was over 30%. The texture and surface properties of thecatalysts were characterized by SEM, XRD, Raman, TG, NH3-TPD and XPS. The suitable amount of weak acid sites and redox sites of the Ti(SO4)2/CS were beneficial to the direct oxidation of DME to DMMx. The calcination temperature changed the distribution of functional groups on the surface of CS which then affected the dispersion form of Ti(SO4)2. The type and amountof acid centers especially the ratio of weak acid and medium strong acid could also be adjusted, which can lead to different gradients of the surface acidity of the catalyst. The reasonable matching of the acidic and redox sites on the catalyst can evidently promote the growth of C–O chain.

中文翻译：

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煅烧温度对Ti(SO4)2/CS催化二甲醚直接氧化制聚甲醛二甲醚性能的影响

摘要 采用浸渍法设计制备了一系列Ti(SO4)2/活性炭球(CS)双功能催化剂，研究了催化剂焙烧温度对二甲醚(DME)直接氧化制聚甲醛二甲醚(DMMx)的影响。 ) 进行了调查。结果表明，Ti(SO4)2/CS催化剂的性能与煅烧温度密切相关。30%Ti(SO4)2/CS催化剂在O2气氛下280℃煅烧表现出优异的活性，DME的转化率达到11.7%，DMM1-3的选择性高达75.8%，其中，DMM2,3的选择性超过 30%。采用SEM、XRD、Raman、TG、NH3-TPD和XPS对催化剂的织构和表面性质进行了表征。Ti(SO4)2/CS中适量的弱酸性位点和氧化还原位点有利于DME直接氧化为DMMx。煅烧温度改变了CS表面官能团的分布，进而影响了Ti(SO4)2的分散形式。酸中心的种类和数量，特别是弱酸和中强酸的比例也可以调整，从而导致催化剂表面酸度梯度的不同。催化剂上酸性和氧化还原位点的合理匹配可以明显促进C-O链的生长。酸中心的种类和数量，特别是弱酸和中强酸的比例也可以调整，从而导致催化剂表面酸度梯度的不同。催化剂上酸性和氧化还原位点的合理匹配可以明显促进C-O链的生长。酸中心的种类和数量，特别是弱酸和中强酸的比例也可以调整，从而导致催化剂表面酸度梯度的不同。催化剂上酸性和氧化还原位点的合理匹配可以明显促进C-O链的生长。