Noble volatile organic compounds

DeVOx A catalytic oxidation process for destroying volatile organic compounds in effluent gases. The catalyst contains a non-noble metal and can easily be regenerated. Typical operating temperatures for 95 percent VOC conversion are 175 to 225°C for oxygenates, and 350°C for toluene. Developed in 1995 by Shell, Stork Comprimo, and CRI Catalysts. First installed in 1996 at Shell Nederland Chemie s styrene butadiene rubber facility at Pemis. 

The GEiM-lOOO low-temperature thermal desorption unit is an ex situ technology that treats soils contaminated with volatile organic compounds (VOCs). This process involves a countercurrent drum, pulse-jet baghouse, and a catalytic oxidizer mounted on a single portable trailer. As the soil is heated in the GEM-1000 unit, contaminants are vaporized. The contaminants are then directed to the system s catalytic oxidizer, which is designed to convert virtually all of the VOCs to carbon dioxide and water vapor. The oxidizer contains approximately 4.9 ft of noble metal catalyst and can destroy between 95 and 99% of the hydrocarbons when operating between 600 and 1250°F. 

Catalytic total oxidation of volatile organic compounds (VOC) is widely used to reduce emissions of air pollutants. Besides supported noble metals supported transition metal oxides (V, W, Cr, Mn, Cu, Fe) and oxidic compounds (perovskites) have been reported as suitable catalysts [1,2]. However, chlorinated hydrocarbons (CHC) in industrial exhaust gases lead to poisoning and deactivation of the catalysts [3]. Otherwise, catalysts for the catalytic combustion of VOCs and methane in natural gas burning turbines to avoid NO emissions should be stable at higher reaction temperatures and resists to thermal shocks [3]. Therefore, the development of chemically and thermally stable, low cost materials is of potential interest for the application as total oxidation catalysts. 

Catalytic oxidation reactions on noble metal surfaces are sufficiently fast and exothermic that they can be operated at contact times on the order of one millisecond with nearly adiabatic temperatures of 1000°C. At short contact times and high temperatures complete reaction of the limiting feed is observed, and highly nonequilibrium products are obtained. We summarize experiments where these processes are used to produce syngas by partial oxidation of methane, olefins by partial oxidation of higher alkanes, and combustion products by total oxidation of alkanes. The former are used to produce chemicals, while the latter is used for high temperature catalytic incineration of volatile organic compounds. 

Catalysts for total hydrocarbon and volatile organic compounds (VOC) combustion in waste gases contain noble metals supported on alumina. The noble metals are platinum, palladium, combinations of platinum and palladium, or rhodium and the typical content is 0.3-0.5 wt%. The BASF RO-25 catalyst, specified for VOC combustion, is reported to contain 0.5% palladium on 0-AI2O3 characterized by a surface area of 109 w g (428). 

For applications in heterogeneous catalysis, perovskites generally comprise a lanthanide (La is the most common) in the A site and a transition metal (Mn, Co, etc.) in the B site. The efficiency of such perovskite oxides, with or without cationic substitution, is well documented for a variety of catalytic reactions [2-9]. Actually, the specific catalytic activities of perovskites were sometimes found to be comparable to that of noble metals for various oxidation reactions. Early on, Arai et al. illustrated the activity of strontium-substituted LaMnOs, which was found to be superior to that of Pt/alumina catalysts at a conversion level below 80% [5]. Several authors have also discussed the application of La-based perovskite oxides as catalysts for volatile organic compound (VOC) oxidation (see, for example. Refs [10-14]). Zhang et al. have also shown that some perovskite oxides substituted with Pd or Cu are also good catalysts for the reduction of NO by CsHg [15-18] and by CO [19,20]. More recently, Kim et al. studied the effect of Sr substitution in LaCoOs and LaMnOs perovskites for diesel oxidation (DOC) and lean NO, trap (LNT) processes [9]. The observations made by these authors clearly indicate that the perovskites used in their study could efficiently outperform Pt-based catalysts. Typically, Lai. Sr cCoOs catalysts achieved higher... 

The halogenated volatile organic compounds have an important role in air pollution, since they are active in ozone depletion of stratosphere [50]. The oxidation of these molecules generated HCl, and in consequence the catalyst should be stable under reaction conditions, and limit the formation of hazardous volatile organic (phosgene, chlorinated dioxins, or dibenzofurans) and inorganic (metal chlorides or oxychlorides) compounds [51]. The structure of the perovskite fi amework induces such stabilization, at least compared to noble metal catalysts, and, in addition, decreases the reactivity of the produced chlorine or hydrochloric acid ... 

Liotta, L. (2010). Catalytic oxidation of volatile organic compounds on supported noble metals Appl. Catal B Environmental, 100, pp. 403 12. 

The development of active catalysts for total combustion of volatile organic compounds (VOCs) has been desired from foe viewpoint of environmental protection. Noble metal which possess high activity for total oxidation are widely applied to foe low temperature complete oxidation [1]. Moreover, it was shown that supports play an important role in catalytic activity and zeolites were widely used as powerful catalytic support [2-4]. Therefore, zeolites FAU and BEA exchanged with different alkali metal cations were prepared and 0.5wt% of palladium was incorporated in these supports. The catalysts obtained were calcined, characterised and tested for propene total oxidation. Some of these solids were also tested for VOCs adsorption. 

The most successful class of active ingredient for both oxidation and reduction is that of the noble metals silver, gold, ruthenium, rhodium, palladium, osmium, iridium, and platinum. Platinum and palladium readily oxidize carbon monoxide, all the hydrocarbons except methane, and the partially oxygenated organic compounds such as aldehydes and alcohols. Under reducing conditions, platinum can convert NO to N2 and to NH3. Platinum and palladium are used in small quantities as promoters for less active base metal oxide catalysts. Platinum is also a candidate for simultaneous oxidation and reduction when the oxidant/re-ductant ratio is within 1% of stoichiometry. The other four elements of the platinum family are in short supply. Ruthenium produces the least NH3 concentration in NO reduction in comparison with other catalysts, but it forms volatile toxic oxides. 

In several previous chapters, we have discussed element volatility. Here we focus on some of the most volatile constituents in meteorites - organic compounds, noble gases, and ices. Each of these actually constitutes a voluminous subject of its own in cosmochemistry, and we can only provide overviews of these interesting components. 

IQ The most volatile elements and compounds organic matter, noble gases, and ices... 

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