Chuanjing Huang

Oscillations during partial oxidation of methane to synthesis gas over Ru/Al2O3 catalyst

Ministry of Science and Technology of China [2005CB221401]; National Natural Science Foundation of China [20873111]; Key Science & Technology Specific Projects of Fujian Province [2009HZ10102]

Ammonia-assisted synthesis towards a phyllosilicate-derived highly-dispersed and long-lived Ni/SiO2 catalyst

Ammonia contributes to the formation of Ni-phyllosilicates on the outer layer of Stober silica by simply using an impregnation method. Through high-temperature reduction, highly dispersed and uniform ultrafine Ni nanoparticles are obtained. The strong metal–support interaction and the porous SiO2 produced by the reduction of Ni-phyllosilicates, which could disperse and confine Ni particles, led to a catalyst with high anti-sintering and coke-resistance performance for the partial oxidation of methane to syngas.

A Novel Catalyst Pt/CoAl2O4/Al2O3 for Combination CO2 Reforming and Partial Oxidation of CH4

Pt/CoAl2O4/Al2O3, Pt/CoOx/Al2O3, CoAl2O4/Al2O3 and CoOx/Al2O3 catalysts were studied for combination CO2 reforming and partial oxidation of CH4. The results indicate that Pt/CoAl2O4/Al2O3 is the most effective, and XRD results indicate that Pt species are well dispersed over the Pt/CoAl2O4/Al2O3. High dispersion is related to the presence of CoAl2O4, formed during calcining at high temperature before Pt addition. In the presence of Pt, CoAl2O4 in the catalyst could be reduced partially at 973 K. Based on these results, it appears that zerovalent platinum with high dispersion and zerovalent cobalt resulting from CoAl2O4 reduction are responsible for high activity in the Pt/CoAl2O4/Al2O3 catalyst.

Oxidative Dehydrogenation of Ethane to Ethylene over Mesoporous Ni-Based Catalysts

Abstract Mesoporous nickel oxide was prepared using sodium dodecyl sulfate as the template and urea as the hydrolysis agent. The method was extended successfully to the synthesis of a mesoporous multicomponent Ni-based catalyst, NiMgO. The mesostructured catalysts were compared with a nanosized NiO catalyst prepared by a sol-gel process. These catalysts were used for oxidative dehydrogenation of ethane to ethylene. The meso-NiO showed higher ethylene selectivity than the nano-NiO at the same ethane conversion. The temperature range for the reaction on meso-NiO was larger, which gave a higher ethylene yield. The catalytic performance of meso-NiO was improved by Mg modification. On meso-NiMgO, a 56.6% ethane conversion with 30.1% ethylene yield was obtained at 450 oC, C 2 H 6 :O 2 :N 2 = 1:1:4, and GHSV = 18000 ml/(g·h). This ethylene yield was much higher than the best obtained with nano-NiO (15.9%) or meso-NiO (22.5%).

Partial oxidation of methane to syngas over mesoporous Co-Al2O3 catalysts

Abstract Mesoporous Co-Al 2 O 3 catalysts were prepared by one-pot synthesis and, for the first time, used in the partial oxidation of methane to synthesis gas. Compared with the catalysts prepared by impregnation methods, the catalysts prepared by one-pot synthesis showed superior catalytic performance for this reaction. The results showed that mesoporous Co-Al 2 O 3 catalysts have high surface areas, large pore volumes, and an ordered hexagonal mesostructure. In the catalysts, Co species are highly dispersed, resulting in high dispersion of the metal after reduction. A confinement effect, provided by the mesopores, on metal nanoparticles could effectively enhance resistance to metal sintering.

Effect of calcination temperature and pretreatment with reaction gas on properties of Co/γ-Al2O3 catalysts for partial oxidation of methane.

The effects of calcination temperature and feedstock pretreatment on the catalytic performance of Co/γ-Al(2)O(3) catalysts were studied for partial oxidation of methane (POM) to synthesis gas, with emphasis on the role of feedstock pretreatment. The physicochemical properties of the catalysts were characterized by N(2) adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), H(2) temperature-programmed reduction (H(2) -TPR), and Raman spectroscopy. The results showed that the pretreatment of the catalyst by reaction gas significantly improved the catalytic activity and stability for the POM reaction. On the other hand, the effect of calcination temperature was less significant. Although the initial activity was increased by an increased calcination temperature, the catalyst without the feedstock pretreatment suffered a rapid deactivation. The reaction-atmosphere pretreatment was revealed as a process that mainly modified the surface structure of the catalyst. In that process, the formation of a CoAl(2)O(4) -like compound led to high Co metal dispersion after reduction, and the transformation of the carrier into α-Al(2)O(3) occurred over the catalyst surface. Both the high dispersion of cobalt and the presence of α-Al(2)O(3) surface phase were assumed as the important factors resulting in an excellent catalytic performance in terms of high activity and high stability.

DEVELOPING SELECTIVE OXIDATION CATALYSTS OF LIGHT ALKANES: FROM FUNDAMENTAL UNDERSTANDING TO RATIONAL DESIGN

Selective oxidation of light alkanes remains to be a great challenge for the wider use of alkanes as feedstocks. To achieve high activity and at the same time high selectivity, some key issues have to be addressed: (1) the stability of the desired products with respect to the reactants; (2) the roles of the active components in the catalysts, the structure and the functionality of the active centers; (3) the reducibility of the metal cations, the Lewis acid sites and their synergic effects with the basic sites of the lattice oxygen anions; (4) spatial isolation of the active centers; and (5) the mechanisms for the formation and transformation of the intermediates and their kinetic controls. In this contribution, we took selective oxidation of propane to acrolein as our target reaction, and reviewed mainly our own work, trying to provide some thinking and answers to these five questions.

In Situ Raman and Pulse Reaction Study on the Partial Oxidation of Methane to Synthesis Gas over a Pt/Al2O3 Catalyst

Catalytic partial oxidation of methane (POM) to synthesis gas (syngas) over Pt/Al(2)O(3) was investigated by in situ microprobe Raman and pulse reaction methods with attention focused on the mechanism of syngas formation in the oxidation zone (i.e., the catalyst zone in which O(2) was still available in the reaction feed). It was found that the amount of platinum oxide in the catalyst under POM conditions was below the detection level of Raman spectroscopy. Raman bands of carbon species that originated from methane dissociation were detected at the entrance of the catalyst bed under working conditions. The results of the pulse reaction study on POM as well as steam and CO(2) reforming of methane at 700 °C with a contact time of less than 1 ms over the catalyst suggest that pyrolysis of methane on reduced platinum sites followed by coupling of two surface hydrogen atoms to H(2) and partial oxidation of surface carbon species to CO are the major reactions responsible for syngas formation in the oxidation zone. Under the experimental conditions, steam and CO(2) reforming of methane play only a minor role in syngas formation in the same reaction zone. The contribution of the last two reactions increases with increasing contact time.

Effect of support on performance of MoVTeO catalyst for selective oxidation of propane to acrolein

Abstract Selective oxidation of propane to acrolein over supported MoV 0.2 Te 0.1 O x catalysts has been investigated. It was found that supports affected the structure, reducibility and O 2 -desorption behaviour of the catalysts, which were closely related to catalyst performance. Among the catalysts studied, MoV 0.2 Te 0.1 /SiO 2 showed the best performance for oxidation of propane to acrolein.

Preparation and characterization of a highly dispersed and stable Ni catalyst with a microporous nanosilica support

A microporous Stober silica was synthesized by controlling the post-drying conditions. Using the silica as a support, a highly dispersed Ni catalyst was successfully prepared by a simple impregnation method. During the impregnation process, the Ni2+ cations could access the micropores of the support and they were turned into monodispersed Ni nanoparticles (<3 nm) after reduction. XRD, TEM, H2-TPR and XPS results revealed that the micropores within the Stober silica play an important role in the preparation of such a highly dispersed Ni catalyst. The as-prepared Ni/SiO2 catalyst showed high catalytic performance and long-term stability for the partial oxidation of methane (POM) to synthesis gas, even at a very low metal loading (1.5 wt%). Such a low metal loading, which is not favorable to the carbon deposition, has been seldom reported so far for Ni- and Co-based catalysts for the POM reaction. More importantly, this strategy provides a simple and low cost method for further designing other silica-supported metal catalysts with high dispersion and anti-sintering ability.