掺杂Sn对V/UiO-66催化剂抗碱金属性能的影响

Effect of Sn Doping on Alkali Metal Resistance of V/UiO-66 Catalyst

采用浸渍法,以UiO-66为载体,制备了V/UiO-66及改性Sn-V/UiO-66催化剂,并对催化剂的碱金属钾中毒进行了模拟,探讨了钒钛催化剂的反应机理和失活机理。结果表明,K负载后催化剂的晶型变化不大并且催化剂比表面积的变化呈现不规律波动。负载了碱金属以后,催化剂的金属氧化还原性能和表面酸量迅速降低,这是催化剂活性降低的主要原因。添加Sn能够增强VO_(x)与其他组分的相互作用,进而提高VO_(x)的可还原性及V^(5+)的占比,使Sn-V/UiO-66催化剂表面的VO_(x)提供更多的酸性位点。中毒后的K-Sn-V/UiO-66催化剂仍然具有较高的总酸量和较强的氧化还原性,表明Sn-V/UiO-66催化剂具有优异的抗碱金属中毒能力。

V/UiO-66 catalyst and modified Sn-V/UiO-66 catalyst were prepared by impregnation method with UiO-66 as carrier,and their potassium poisoning was simulated.The reaction and deactivation mechanisms of vanadium-titanium catalyst were analyzed.Results demonstrate that the crystallographic form of catalysts barely changes after K-loading,and the specific surface area of the catalysts has an irregular fluctuation.The catalyst activity is decreased rapidly after the alkali metal was loaded due to the degraded metal redox performance and the rapidly decreased surface acid content of the catalysts.The addition of Sn can enhance the interaction between VO_(x)and other components,which thereby increases the V^(5+)content and reducibility of VO_(x).Thus,VO_(x)on the surface of Sn-V/UiO-66 catalysts can provide more acid sites.The poisoned K-Sn-V/UiO-66 catalyst still has high total acid content and strong redox property,presenting the high resistance of Sn-V/UiO-66 catalyst against alkali metal poisoning.