Effect of TiO2 Crystallite Size on the Activity of CO Oxidation

Abstract

Nanocrystalline TiO 2 with average crystallite sizes 7 and 15 nm were synthesized by the solvothermal method using titanium n-butoxide and 1,4-butanediol as titanium precursor and solvent, respectively. Four transition metals (Ag, Co, Ni, Pt) were supported on the TiO 2 supports by incipient wetness impregnation with metal loadings 1 and 25 atomic%. For any metal type, metal dispersion and CO oxidation activities were higher when the catalysts were prepared on the larger crystallite size TiO 2 for both high and low metal loadings, despite their lower surface areas. The presence of higher amount of Ti 3? on the larger crystallite size TiO 2 probably stabilized small metal particles during impregnation, calcination, and reduction steps via stronger metal-support interaction; hence higher CO oxidation activities and lower light-off temperature were obtained.

The influence of Si-modified TiO2 on the activity of Ag/TiO2 in CO oxidation

“…The samples were measured in a controlled humidity room. The amount of metal active sites for Ag/TiO 2 catalysts was determined using N 2 O pulse chemisorption according to the method described previously by our group [22]. Approximately 100 mg of the catalyst sample was reduced in hydrogen flow (50 cm 3 /min) at 200 8C.…”

Study of catalytic activity at the Ag/Al-SBA-15 catalysts for CO oxidation and selective CO oxidation

“…However, they are often inter-related depending on choice of the support [1]. Comsup et al found that stronger Ag-TiO 2 interactions improved the catalytic activity for CO oxidation [14]. Doping of P and Si into TiO 2 resulted in different activities [15,16].…”

Progress in carbon monoxide oxidation over nanosized Ag catalysts

“…The support can disperse the metal particles and induce interactions between Ag and the support [25]. At present, supports for Ag catalysts are divided into two main categories: (1) inert supports such as silica materials [25][26][27]42,52,53,55,56,59] and Al2O3 [60]; and (2) active supports such as CeO2 [32], FeOx [45][46][47], CoOx [48], TiO2 [61][62][63][64], and MnOx [29,58,[65][66][67][68][69]. The CO oxidation activities of Ag catalysts supported on different supports are listed in Table 1.…”

“…The highest catalytic activity for CO oxidation was found on the Ag/Al2O3 catalyst, and the catalytic activity for CO oxidation was strongly related to the reduction activity of the catalyst. Comsup et al [62] found that stronger Ag-TiO2 interactions improved the catalytic activity for CO oxidation. Doping of P and Si into TiO2 resulted in different activities [63,64].…”

“…运用X射线衍射(XRD), 程序升温脱 附 (TPD) 和程序升温还原(TPR) 技术研究了Ag/Al 2 O 3 , Ag/CeO 2 和Ag/TiO 2 催化剂的氧性质及CO氧化活性, 发 现Ag/Al 2 O 3 催化剂上CO氧化活性最高, 催化剂上CO氧 化活性顺序与其还原易难顺序一致. Comsup等[62] 发现, Ag与TiO 2 间很强的相互作用有利于催化活性的提高. P 和Si对TiO 2 进行掺杂可导致不同的活性[63,64] .…”