The CrHZSM-5 catalysts with trace amount of Cr were firstly used for catalytic cracking of isobutane, and the effect of Crloading on the catalytic performances of CrHZSM-5 catalysts for the cracking of isobutane was also studied. The results suggested that when the loading of Cr in the CrHZSM-5 catalysts was less than 0.038 mmol/g Cr, especially at Cr loading of 0.004 mmol/g, both the reactivity of isobutane cracking and the selectivity to light olefins of CrHZSM-5 samples were greatly enhanced compared with the unpromoted HZSM-5, and very high yields of olefins(C2+C3) and ethylene were obtained. For instance, the yield of olefins(C2+C3) and ethylene reached 56.1% and 30.8%, respectively, at 625 ℃ when 0.004 mmol/g Cr was loaded on HZSM-5sample.

Bulk V-Nb-O, Mo-Nb-O, Te-Nb-O, and V-Mo-Te-Nb-O mixed metal oxides were synthesized and characterized with Raman spectroscopy, XRD, and BET methods. The interaction of the V and Mo cations with the Nb2O5 lattice followed three stages: (1) cations were initially incorporated into the Nb2O5 lattice forming a solid solution or compound as well as on the Nb2O5 surface, (2) a two-dimensional surface cation overlayer was formed after saturation of the solid solution, and (3) microcrystalline metal oxide phases (e.g., V2O5 and MoO3) were formed after completion of the two-dimensional surface cation monolayer. The catalytic properties of these bulk mixed metal oxides were investigated for the oxidative dehydrogenation (ODH) of propane to propylene, and their activity follows the trend: V-Nb-O > Mo-Nb-O>>Nb2O5 > Te-Nb-O. The highest propane conversions and propylene yields were found when the two-dimensional surface metal oxide monolayers were formed, which suggests that the surface metal oxide species are the surface active sites in these bulk mixed metal oxide catalysts for propane ODH. Furthermore, the number of surface active sites present in the bulk mixed metal oxides was determined by comparative studies between the bulk mixed metal oxides and the corresponding model Nb2O5-supported metal oxides. These numbers can be used further for the calculation of the TOF (turn-over-frequency) values and quantitative comparison of the catalytic behavior of the different bulk mixed metal oxide catalysts for propane ODH. The catalytic results over the model Nb2O5-supported metal oxides demonstrate that the propane ODH reaction is structure insensitive because the TOF is independent of the number and the structure of surface active sites. The composition and calcination temperature of the bulk mixed metal oxide catalysts affects the surface density of the active sites, which controls their catalytic behavior for propane ODH.

Al2O3 and SiO2 were used to load chromium oxides with incipient-wetness impregnation method. These supported chromia catalysts were evaluated for the dealkylation of C10+ heavy aromatics in hydrogen flow and were characterized with BET, XRD, FT-IR, UV–vis DRS and H2-TPR techniques. The results indicate that the catalytic activity of supported chromia catalysts on SiO2 is higher than that of on Al2O3. Structural characterization results show that surface reduced CrOx species are the active sites for hydrodealkylation of C10+ heavy aromatics. (C10+ heavy aromatics denote the aromatics whose carbon numbers are equal to or greater than 10.) The structural models of CrOx species on the Al2O3 or SiO2 support surface were also proposed.

Various highly dispersed Mo supported catalysts with various carriers were prepared for deep hydrodesulphurization of diesel. The carriers included a high surface area and large pore volume g-Al2O3, two types of meso-microporous composite molecular sieves prepared by incipientwetness impregnation method. A new mesoporous MoSiOx catalyst synthesized with in situ composite method was also studied. The hydrodesulphurization experiments were carried out in a micro-reactor over different catalysts including Mo supported series and a commercial catalyst. Spectroscopic techniques (FT-IR and UV–vis DRS) were utilized to determine the structure of MoOx species. The catalyst haracterizations of BET, XRD, FT-IR, UV–vis DRS and FTIR pyridine adsorption indicated that the existences of metal active component of Mo in the catalysts were highly dispersed nano MoO3 clusters and the Mo series catalysts had high surface areas and plenty of large pores which were propitious to the diffusions of reactant and product molecules. CatNiMo exhibited the highest B/L acidity ratio and higher total concentration of Bronsted acid sites and Lewis acid sites, and its HDS activity also gave the highest in this study to produce a sulphur-free diesel, which was verified by the sulphur content in products analyzed by GC–MS methods.

It is reported that cyclic voltammetry (CV) is a strong tool to investigate catalytic reactions not only in homogeneous catalysis, but also in heterogeneous catalysis. The application of CV measurements in homogeneous catalysis is illustrated through investigation of NO removal (NO reduction and decomposition), which is an urgent task of today in environment catalysis. Results of our study indicate that both the area of redox peak and the symmetry of redox potentials of catalyst are important parameters in determining the catalytic activity, but each has his strong point in different reactions (NO reduction and decomposition). We suggest that CV is a powerful means to select catalysts for NOx removal.