Ag/SiO2, Cu/SiO2 and Pd/SiO2 cogelled xerogel catalysts for benzene combustion: Relationships between operating synthesis variables and catalytic activity

Applied Catalysis B: Environmental

et al. 2010

108

a b s t r a c t ZSM-5/MCM-48 composite materials with various acidities have been successfully assembled on zeolite seeds via a two-step crystallization process. The characterization results reveal that the ZSM-5 seeds are present in the framework of the resulting composite materials with its content gradually increasing with the Si/Al molar ratio, and Al atoms prefer the tetrahedral coordination in composite products. The amount of strong acid sites increases as the Si/Al molar ratio decreases, while that of weak acid sites is almost unchanged. The activity tests demonstrate that the catalytic activity of Pd-loaded ZSM-5/MCM-48 composite catalysts is much higher than that of Pd/ZSM-5 and Pd/MCM-48, and all these catalysts are active and stable in the total oxidation of benzene. Both Pd 0 and Pd 2+ are responsible for the oxidation reaction, and the catalytic activity is closely related to the support acidity, the CO 2 desorption capability and the Pd dispersion. This research thus indicates that the novel composite materials have promised as active Pd-supported catalysts in the elimination of volatile organic compound (VOCs).

Section: Catalytic Oxidation Of Benzenementioning

confidence: 67%

Comprehensive investigation of Pd/ZSM-5/MCM-48 composite catalysts with enhanced activity and stability for benzene oxidation

Applied Catalysis B: Environmental

et al. 2010

108

“…It is worth noting that the CO 2 selectivity of GtPd/HP 92 -80 (98.3-100%) is higher than that of ImPd/HP 92 -80 (90.6-100%) at different reaction temperatures. It is well known that a high activity of a supported catalyst often resulted from a large active surface area, i.e., a high dispersion of the active phase (small particle size) [41]. For GtPd/HP 92 -80 sample, the Pd nanoparticles are well dispersed on the inner/outer surfaces of mesoporous SBA-15, which may result in the superior catalytic activity.…”

Section: Catalytic Performance and Stability Of Synthesized Catalystsmentioning

confidence: 98%

Templated Silica with Increased Surface Area and Expanded Microporosity: Synthesis, Characterization, and Catalytic Application

Chemical Engineering Journal

et al. 2010

a b s t r a c tIn this paper, we report a convenient and effective approach to synthesizing mesoporous SBA-15 materials with increased surface area (up to 836.7 cm 3 /g) and expanded microporosity (up to 0.22 cm 3 /g), where the textural properties of the synthesized materials can be systematically controlled. These micro/mesoporous composite materials exhibit excellent performance in catalysis, adsorption and separation. Moreover, the synthesized materials that supported Pd catalysts obtained through impregnation and grafting approaches were tested to explore their flexibility in toluene elimination. Grafting is an effective method to obtain highly dispersed Pd nanoparticles compared with traditional impregnation approach. The catalyst prepared via the grafting procedure possesses higher activity and CO 2 selectivity than that was prepared by impregnation method. Moreover, the catalytic performance of synthesized catalysts can be well sustained during the stability tests. Therefore, these novel Pd-supported catalysts are promising materials for effective removal of some types of volatile organic compounds (VOCs) such as toluene.

“…As is known, achieving precise control of the Pd particle size and overall particle size distribution of catalysts is one of the most important challenges to provide excellent catalysis properties [35]. Moreover, a high activity of a supported catalyst often calls for a large active surface area, i.e., high dispersion of the active phase [36]. Herein, the Pd nanoparticles are well-dispersed in pore channels of SBA-15 and the size-restricted mesopores of host silica can effectively prevent the agglomeration of active Pd particles, which resulted in the superior activity of GtPdS-D.…”

Section: Catalytic Oxidation Of Toluenementioning

confidence: 99%

Ligand-assisted preparation of highly active and stable nanometric Pd confined catalysts for deep catalytic oxidation of toluene

Journal of Hazardous Materials

Wang

et al. 2010

a b s t r a c tIn this study, mesoporous SBA-15 supported Pd catalysts were synthesized through impregnation and grafting approaches. Moreover, the influences of different solvents (ethanol, H 2 O, tetrahydrofuran, dimethyl sulphoxide and N,N-dimethylformamide) on the dispersion of supported Pd nanoparticles were also systematically investigated. The prepared materials were comprehensively explored by various techniques, including XRD, EDS, ICP-OES, H 2 chemisorption, N 2 adsorption/desorption, TG-DSC, FT-IR, TEM and STEM. It is found that the traditional impregnation method has some disadvantages in obtaining highly dispersed Pd active phase. Whereas, the grafting method could highly disperse Pd nanoparticles within the mesoporous channels of support material, and the grafting procedure should be promising in designing highly dispersed Pd particles on the silica-based mesoporous materials. The catalyst prepared via the grafting procedure possesses much higher activity and selectivity than that prepared by impregnation method for deep catalytic oxidation of toluene.