K/Mo Catalysts Supported over Sol–Gel Silica–Titania Mixed Oxides in the Oxidative Dehydrogenation of Propane

• Published in: Journal of catalysis Vol. 191; no. 1; pp. 12 - 29
• Main Authors: Watson, Rick B., Ozkan, Umit S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.04.2000; Elsevier
• Subjects: 03 NATURAL GAS; alkali promotion (potassium); Catalysis; CATALYST SUPPORTS; Catalysts: preparations and properties; CATALYTIC EFFECTS; CHEMICAL PREPARATION; CHEMICAL PROPERTIES; CHEMICAL REACTION YIELD; Chemistry; DEHYDROGENATION; DRIFTS; ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; Exact sciences and technology; General and physical chemistry; MOLYBDENUM; NH3 adsorption; OXIDATION; PHYSICAL PROPERTIES; POTASSIUM; PROPANE; propane oxidative dehydrogenation; PROPYLENE; silica–titania mixed oxides; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; TPD; TPR; XPS; NH3 adsorption; DRIFTS; TPR; TPD; propane oxidative dehydrogenation; alkali promotion (potassium); XPS; silica–titania mixed oxides; molybdenum; Catalytic reaction; Hydrocarbon; Transition metal; Modified catalyst; X ray; Alkali metal; Molybdenum; Silica; Supported catalyst; Titanium Oxides; Promoter; Gas solid adsorption; Ammonia; Dehydrogenation; Sol gel process; Preparation; Alkane; Photoelectron spectrometry; Oxidation; Potassium; Propane
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1006/jcat.1999.2781

The use of silica–titania mixed-oxide-supported molybdenum catalysts has been studied with regard to their activity for the oxidative dehydrogenation of propane. The effect of alkali doping on the catalyst surface characteristics and, in turn, on the catalytic performance has been examined. The catalysts used in this study have been synthesized by a “one-pot” sol–gel/coprecipitation technique.The main focus of the work has been characterization of the surface molybdena species, physical–chemical properties of the Si:Ti support, surface acidity, reducibility, adsorption/desorption behavior, and surface intermediates present during the reaction. Catalysts were characterized by BET surface area measurements, X-ray diffraction, laser Raman spectroscopy, temperature-programmed reduction, X-ray photoelectron spectroscopy, propane temperature-programmed desorption, and diffuse reflectance infrared Fourier transform spectroscopy. By varying the K/Mo molar ratio a maximum in selectivity and yield of propylene was obtained. The maximum yield of propylene obtained in dilute feed experiments was ∼30%. Experiments with more concentrated feed mixtures were also performed to achieve a higher percentage of propylene (6–7%) in the product stream.