Regulating crystal phase of TiO_(2) to enhance catalytic activity of Ni/TiO_(2) for solar-driven dry reforming of methane

调控Ni/TiO_(2)载体晶相结构实现高活性光热干重整制合成气

Ni/TiO_(2) catalyst is widely employed for photo-driven DRM reaction while the influence of crystal structure of TiO_(2) remains unclear.In this work,the rutile/anatase ratio in supports was successfully controlled by varying the calcination temperature of anatase-TiO_(2).Structural characterizations revealed that a distinct TiO_(x) coating on the Ni nanoparticles(NPs)was evident for Ni/TiO_(2)-700 catalyst due to strong metal-support interaction.It is observed that the TiOx overlayer gradually disappeared as the ratio of rutile/anatase increased,thereby enhancing the exposure of Ni active sites.The exposed Ni sites enhanced visible light absorption and boosted the dissociation capability of CH4,which led to the much elevated catalytic activity for Ni/TiO_(2)-950 in which rutile dominated.Therefore,the catalytic activity of solar-driven DRM reaction was significantly influenced by the rutile/anatase ratio.Ni/TiO_(2)-950,characterized by a predominant rutile phase,exhibited the highest DRM reactivity,with remarkable H_(2) and CO production rates reaching as high as 87.4 and 220.2 mmol/(g·h),respectively.These rates were approximately 257 and 130 times higher,respectively,compared to those obtained on Ni/TiO_(2)-700 with anatase.This study suggests that the optimization of crystal structure of TiO_(2) support can effectively enhance the performance of photothermal DRM reaction.

Ni/TiO_(2)催化剂被广泛应用于光热干重整反应中,然而不同TiO_(2)晶相结构对反应性能的影响尚不清楚。本研究通过改变锐钛矿TiO_(2)的焙烧温度,制备了不同金红石/锐钛矿混合比例的载体。结构表征表明,锐钛矿TiO_(2)具有较强的金属-载体间相互作用,促使Ni/TiO_(2)在还原过程中形成TiOx包覆层,大幅减少暴露的Ni活性位点。随着金红石/锐钛矿比例的增加,金属-载体间相互作用变弱,TiO_(x)包覆层逐渐消失,从而促进了Ni活性位点的暴露。暴露的Ni位点不仅可增强可见光吸收,同时也提高了CH_4的解离能力。性能评价显示,金红石/锐钛矿比例对光热干重整反应活性影响较大。具有金红石相的Ni/TiO_(2)-950催化剂表现出最高的反应活性,H_(2)和CO产率分别达到87.4和220.2 mmol/(g·h),分别为锐钛矿相Ni/TiO_(2)-700催化剂的257倍和130倍。本研究通过改变TiO_(2)晶体结构有效提高了光热干重整反应活性,从而为高效光热催化剂的设计提供了一条简单易行的策略。