Novel and ideal zirconium-based dense membrane reactors for partial oxidation of methane to syngas

A novel and ideal dense catalytic membrane reactor for the reaction of partial oxidation of methane to syngas (POM) was constructed from the stable mixed conducting perovskite material of BaCo0.4Fe0.4Zr0.2O3-delta and the catalyst of LiLaNiO/gamma-Al2O3. The POM reaction was performed successfully. Not only was a short induction period of 2 h obtained, but also a high catalytic performance of 96-98% CH4 conversion, 98-99% CO selectivity and an oxygen permeation flux of 5.4-5.8 ml cm(-2) min(-1) (1.9-2.) mumol m(-2) S-1 Pa-1) at 850 degreesC were achieved. Moreover, the reaction has been steadily carried out for more than 2200 h, and no interaction between the membrane material and the catalyst took place.

An integrated air-POM syngas/dimethyl ether process from natural gas

A Cu-Zn-Al methanol catalyst combined with HZSM-5 was used for dimethyl ether (DME) synthesis from a syngas containing nitrogen, which was produced by air-partial oxidation of methane (air-POM). Air-POM occurred at 850 degreesC, 0.8 MPa, CH4/air/H2O/CO2 ratio of 1/2.4/0.8/0.4 over a Ni-based catalyst modified by magnesia and lanthanum oxide with 96% CH4 conversion and constantly gave syngas with a H-2/CO ratio of 2/1 during a period of 450 h. The obtained N-2-containing syngas was used directly for DME synthesis. About 90% CO per-pass conversion, 78% DME selectivity and 70% DME yield could be achieved during 450 h stability testing under the pressure of 5.0 MPa. the temperature of 240 degreesC and the space velocity of 1000 h(-1). (C) 2002 Elsevier Science B. V. All rights reserved.

Partial oxidation of ethane to syngas over nickel-based catalysts modified by alkali metal oxide and rare earth metal oxide

The catalytic activity, thermal stability and carbon deposition of various modified NiO/gamma-Al2O3 and unmodified NiO/gamma-Al2O3 catalysts were investigated with a flow reactor, XRD, TG and UVRRS analysis. The activity and selectivity of the NiO/gamma-Al2O3 catalyst showed little difference from those of the modified nickel-based catalysts. However, modification with alkali metal oxide (Li, Na, K) and rare earth metal oxide (La, Ce, Y, Sm) can improve the thermal stability of the NiO/gamma-Al2O3 and enhance its ability to suppress carbon deposition during the partial oxidation of ethane (POE). The carbon deposition contains graphite-like species that were detected by UVRRS. The nickel-based catalysts modified by alkali metal oxide and rare earth metal oxide have excellent catalytic activities (C2H6 conversion of similar to 100%, CO selectivity of similar to 94%, 7x 10(4) l/(kg h), 1123 K), good thermal stability and carbon-deposition resistance.

Mechanistic studies of methane partial oxidation to syngas over LiNiLaOx/Al2O3 catalyst

Temperature-programmed reduction (TPR) characterization of the LiNiLaOx/Al2O3 catalyst before or after partial oxidation of methane (POM) reaction and a series of O-2, CH4 and CH4/O-2 pulse reaction experiments over the catalyst under different pretreatments were performed. It was found that CH4 dissociatively adsorbs on active center nickel producing H-2 and surface carbon, C(a). The surface carbon reacts with surface lattice oxygen or surface adsorbed oxygen to produce CO. Because the activation barrier for the reaction C(a)+ O(a) =CO(a) is the highest among all the elementary reactions, the rate-determining step of the POM may be the reaction C(a) + O(a) =CO(a).