Complete Catalytic Oxidation of Hydrocarbon Impurities (VOCs) Over Noble Metal Catalysts

Abstract

The importance of heterogeneously catalyzed hydrocarbon chemistry can hardly be overestimated, ranging from processes such as petroleum reforming to fine chemicals synthesis and pollution control. Despite these successes C–H activation of saturated hydrocarbons remains a challenge both for their utilization as an alternative feedstock, and their combustion for power generation and the regulation of environmental emissions. Catalytic oxidation is an important element in the worldwide fight against air pollution. Complete catalytic oxidation (defined as oxidation reaction at the surface of the catalyst) have been extensively investigated in the present study. The interest in this process arises for two reasons: for pollution abatement and for power generation. In recent years, there has been an increasing awareness apropos the environmental and health concerns arising from the pollution of (VOC’s & hydrocarbon emissions) caused by various industries and automobile exhausts. In any industrial plant around the world of almost any kind, there is a burning issue that is needed to be addressed…literally it’s Volatile Organic Compounds (VOCs) and Hazardous Air Pollutants (HAPs) contained in the exhaust gases produced by many industrial processes. VOC release has widespread environmental implications, and has been linked to the increase in photochemical smog, depletion in atmospheric ozone and production of ground-level ozone. This awareness has prompted the issuance of stringent regulations on the emission of VOC’s & hydrocarbon emissions along with several other pollutants such as NOx, SOx and greenhouse gases. Statutory limits on Hydrocarbon and volatile organic compound emissions have increased the need for cost-effective air pollution abatement technology. In most of all kind of circumstances, complete catalytic oxidation/combustion is the most relevant, more versatile and economical treatment option to go for and which results in a company saving money and free of environmental concerns with a reduced overall impact. In our modern society increasingly important is not only the production of new materials and products but also destruction of undesired products of the activities of society, and this may be achieved by complete catalytic oxidation technology. v Here, an attempt is made by carrying research work to understand various theoretical and practical fundamental aspects of complete catalytic oxidation/ combustion to treat industrial emissions containing hydrocarbons and VOCs and to harness the benefits offered by this environmental pollution abatement technology. The ultimate objective set during the project planning stage is to develop complete oxidation/combustion noble metal based catalyst configurations which can completely convert pollutants such as VOC & hydrocarbons into innocuous products with better destruction efficiency even at a lower VOC/Hydrocarbon concentration with stoichiometric amount of oxygen at the lowest possible temperatures. Propane (C3H8), saturated paraffinic hydrocarbon which is very much difficult to oxidize is undertaken as the model reactant for the study. A large amount of work has been directed towards the development of noble metal based catalyst formulations and evaluation of catalysts for varied hydrocarbon concentrations on stream, GHSV and other operating conditions for complete oxidation/combustion of propane. Various noble metal configurations were prepared by varying active metals & their combinations, active metal concentration, additive concentration, sulfation etc. Several Pt & Pt-Pd based noble metal based catalyst formulations with Al2O3 support are prepared and then evaluated. The performances of these catalysts are evaluated by Gas Chromatograph (GC) with FID as the monitoring mechanism. Comparative evaluation of the commercially available oxidation catalysts with R&D developed catalysts also forms the part of the study. Time on stream activity study, Effect of hydrocarbon concentration variation, Effect of additive concentration variation, Performance of 0.1 wt. % Pt-SO42-/Al2O3 vs. 0.1 wt. % Pt/Al2O3, Effect of sulfation, Effect of active metal (Pt) concentration variation, Light-off curve study & Performance comparison with commercial catalysts, Cmax Study, Effect of GHSV variation, Performance comparison of R&D developed catalysts with commercial catalysts for the H/C variation study & GHSV variation study and Performance of Bi-metallic (Pt-Pd) Catalysts for Propane Oxidation forms the experimental part of the research work.