Novel amorphous Ni-B catalysts supported on alumina have been developed for the production of hydrogen peroxide from carbon monoxide, water and oxygen. The experimental investigation confirmed that the promoter/Ni ratio and the preparation conditions have a significant effect on the activity and lifetime of the catalyst. Among all the catalysts tested, the Ni-La-B/γ- Al2O3 catalyst with a 1:15 atomic ratio of La/Ni, dried at 120℃, shows the best activity and lifetime for the production of hydrogen peroxide. The deactivation of the alumina-supported Ni-B amorphous catalyst was also studied. According to the characterizations of the fresh and used catalysts by SEM, XRD and XPS, no sintering of the active component and crystallization of the amorphous species were observed. However, it is water poisoning that leads to the deactivation of the catalyst. The catalyst characterization demonstrated that the active component had changed (i.e., amorphous NiO to amorphous Ni(OH)2) and then salt was formed in the reaction conditions. Water promoted the deactivation because the surface transformation of the active Ni species was accelerated by forming Ni(OH)2 in the presence of water. The formed Ni(OH)2 would partially change to Ni3(PO4)2.

In this work, starch has been used to enhance the oxygenate formation directly from methane and carbon dioxide using dielectric-barrier discharges (DBDs). The use of starch inhibits the formation of liquid hydrocarbons and significantly increases the selecti

Methane conversion in the presence of carbon dioxide was investigated under the conditions of dielectric-barrier discharge plasmas. Different from the previous investigations, the grounded electrode is covered by the dielectric material (quartz) in the present reactor design. The product contains gaseous hydrocarbons, syngas and oxygenates. No liquid hydrocarbons can be detected with the present reactor design. The oxygenates produced includes acetic acid, propanoic acid, ethanol and methanol. There exists an optimum feed ratio of CH4/CO2 to make the maximum selectivity of the objective oxygenate. The highest selectivity of acetic acid was 5.2% achieved at CH4 and CO2 conversions of 64.3% and 43.1%, respectively.

A lot of attentions have been recently paid to the CO2 reforming of methane to syngas. A major reason for it is that this reaction can provide us a syngas with a 1/1 ratio of H2 and CO, which is typically suitable for the synthesis of valuable oxygenated chemicals.1 Among the catalysts developed, Al2O3 supported Ni catalysts were extensively investigated due to their relatively high activity and low cost. The major problem for the further practical application of these nickel catalysts is the deactivation of the catalyst, suffered from carbon deposition on the catalyst during reactions. Many investigators are working on the improvement in this nickel catalyst by using the addition of promoters,2, 3 using novel reactor configurations,4 and using different supports.3 In this work, we attempt to use an AC corona discharge plasma for the CO2 reforming of methane to syngas. A stable operation of plasma CO2 reforming of methane has been achieved.

A density functional theory (DFT) study has been conducted to investigate the structural and electronic properties of PdO/HZSM-5 and thereby the relationship between PdO and the acid sites of HZSM-5. Different cluster models of PdO/HZSM-5 based on experimental and theoretical works are presented. The study shows that the local structure of PdO supported on HZSM-5 is very similar to the four-coordinated square planar structure of bulk PdO. This is consistent with the reported EXAFS analysis in the literature. The average distances between the Pd and the four coordinated oxygen atoms obtained by DFT calculations with different cluster models are close to the reported experimental results. The analysis of the Mulliken population and the electron density difference of the cluster models shows that there exists a charge transfer from the four coordinated oxygen atoms to the Pd. The components of the frontier molecular orbital of these cluster models come mainly from the Pd and the four coordinated oxygen atoms. The DFT study confirms that the acid sites in HZSM-5 keep the PdO well dispersed due to the bond interaction between the acidic proton atom and the oxygen atom of PdO. In addition, after the formation of PdOH+, the acidity of HZSM-5 complex remains high or in some instances increases.