Volatile organic compounds catalytic oxidation

P-23 - Total oxidation of volatile organic compounds - catalytic oxidation of toluene over CuY zeolites... 

This paper describes the catalytic activity of various forms of manganese dioxides towards volatile organic compounds deep oxidation. Important differences in activity are evidenced for very closely related structures the most active sample is a high surface area nsutite. A parallel is drawn between the findings in the literature of battery applications and the catalytic activity results. The superior activity of nsutite is attributed to a different oxygen coordination and to the clustering of cationic vacancies in the bulk which improves electronic and protonic conductivity. 

Environmental applications of metal-doped carbon gels can be divided between reactions carried out in the gas and aqueous phases. The former group includes volatile organic compound (VOC) oxidation (e.g., toluene and xylene oxidation) and NO reduction. The latter group includes the catalytic wet air oxidation (CWAO) of aniline solutions and advanced oxidation processes (AOPs) (e.g., catalytic ozonation and photooxidation of pollutants). 

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... 

Tsou, J., Pinard, L. and Magnoux, P. (2003). Catalytic oxidation of volatile organic compounds (VOCs) Oxidation of o-xylene over Pt/HBEA catalysts, Appl. Catal. B Environ., 46, pp. 371-379. 

Ojala, S. (2005) Catalytic oxidation of volatile organic compounds. Doctoral Thesis. Oulu University Press, Finland. 

Scire S, Minico S, Crisafulli C, Satriano C, Pistone (2003) Catalytic combustion of volatile organic compounds on gold/cerium oxide catalysts. Appl Catal B Environ 40(1-8) 43 19... 

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. 

SWITGTHERM A catalytic process for oxidizing volatile organic compounds (VOCs). It involves regenerative heat exchange, which permits autothermal operation at VOC concentrations in the range 250 to 650 ppm. Developed in Poland and now used in over 100 installations there. 

Incineration systems are based on the principle that all volatile organic compounds are combustible and can, in principle, be eliminated simply by being burned. Combustion can be achieved without catalysts (thermal systems) or with catalysts (catalytic systems). In either case, flue gases are passed into a chamber where they are heated in an excess of air, resulting in the oxidation of VOCs. Thermal systems operate at temperatures of 750°C-1,000°C, while catalytic systems operate at temperatures of about 350°C-500°C. 

The SRCO catalytic combustion unit treats volatile organic compound (VOC) laden process exhaust air. SRCO stands for self-recuperative catalytic oxidizer. The SRCO can be furnished as a complete operating vacuum extraction and catalytic oxidation system or as a stand-alone catalytic oxidizer to interface with an existing vacuum extraction and/or air stripper system. HD-SRCO stands for halogenated destruction self-recuperative catalytic oxidizer. This system is basically the same as the SRCO system, except that it remediates halogenated hydrocarbons using a different catalyst. 

Catalytic oxidation is capable of treating contaminant concentrations ranging from 1 part per million (ppm) to 20,000 ppm. Typically, it is applied to streams containing about 3000 ppm per volume or less of volatile organic compounds (VOCs). At levels approaching 3000 ppm per volume VOCs, the recoverable heat from the process may be sufficient to sustain oxidation without additional fuel. 

The Econ-Abator system is a fluidized-bed catalytic oxidation system. Catalytic fluidized beds allow for destruction of volatile organic compounds (VOCs) at lower temperatures than conventional oxidation systems (typically 500 to 750°F). The technology uses a proprietary catalyst consisting of an aluminum oxide sphere impregnated with chromium oxide. 

The HD CatOx system treats vapor emissions contaminated with halogenated volatile organic compounds (VOCs). HD CatOx is a trade acronym for the term halohydrocarbon destruction catalytic oxidation system. This system is based on the use of a proprietary catalyst for a... 

King, Buck Technologies, Inc. s, MultiMode combustion (MMC) system treats volatile organic compound (VOC) emissions from soil vapor extraction (SVE) operations. The sequential operation of a thermal oxidizer (ThermOx) followed by a catalytic oxidizer (CatOx) is the basic concept of the MMC system. The CatOx technology is discussed in a separate technology summary (T0780). 

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. 

Photocatalytic oxidation (PCO) is a destructive process for the treatment of gas-phase waste streams that can operate successfully at low concentrations of contaminants and at a low energy cost. In this technology, ultraviolet (UV) light illuminates a titanium dioxide catalytic surface at room temperatures and produces hydroxyl radicals, which destroy volatile organic compounds (VOC s). 

Contaminated soil is fed into a rotary dryer where the temperature is raised to between 500 and 800°F. As the soil is heated, moisture and volatile organic compounds (VOCs) are vaporized. The heated exhaust gases from the dryer are forced through a baghouse where soil fines and dust particles are removed. Exhaust gases are then passed through a catalytic oxidizer to remove hydrocarbons. 

The CO P catalytic oxidation system is a complete prefabricated unit used to treat wastewater contaminated with volatile organic compounds (VOCs) and high biological oxygen demand and chemical oxygen demand. The system uses ozone, ultraviolet light, and hydrogen peroxide to create hydroxyl radicals used in oxidation. 

Fromment and Bishoff (1990) presented the possible expression of each of these terms in various cases, whereas Poulopoulos el al. (2001) have presented various rate laws for the catalytic oxidation of volatile organic compounds, as shown in Table 5.3. 

M. Kosusko and C. M. Nunez, "Destruction of Volatile Organic Compounds Using Catalytic Oxidation," JAWMA 40(2) (Feb. 1990). 

It is fair to state that by and large the most important application of structured reactors is in environmental catalysis. The major applications are in automotive emission reduction. For diesel exhaust gases a complication is that it is overall oxidizing and contains soot. The three-way catalyst does not work under the conditions of the diesel exhaust gas. The cleaning of exhaust gas from stationary sources is also done in structured catalytic reactors. Important areas are reduction of NOv from power plants and the oxidation of volatile organic compounds (VOCs). Structured reactors also suggest themselves in synthesis gas production, for instance, in catalytic partial oxidation (CPO) of methane. 

Complete oxidation of hydrocarbons in air is a useful method for atmospheric purification, and has been sucessfully applied in automotive exhaust control. An important new area is the catalytic control of the emissions of volatile organic compounds (VOC) in a more general sense [1]. Many sources, low concentrations and wide temperature ranges can be involved. 

The air pollutants of volatile organic compoimds emitted from many industrial processes and transportation activities could be abated by catalytic combustion processes. Scire et al. reported the catalytic combustion of 2-propanol, methanol, and toluene on ceria-gold catalysts. The catalysts were prepared with coprecipitation and deposition-precipitation methods. The gold significantly enhanced the catalytic activity of ceria for the oxidation of these volatile organic compounds. The supposed reason is that the gold NFs weakened the mobility/reactivity of surface lattice oxygen (Scire et al., 2003). 

Since natural sunlight can only penetrate a few microns depth, the use of thin films of titania applied to ceramic or metallic supports as maintenance free decontamination catalysts for the photocatalytic oxidation of volatile organic compounds is of interest for the abatement or control of these emissions. The sol-gel technology can be readily incorporated as a washcoating step of the catalyst supports that may be subsequently heat-treated to fix the titania to the support. The surface area, porosity and crystalline phases present in these gels is important in controlling their catalytic activity. Furthermore, the thermal stability and development of porosity with heat-treatment was important if the sol-gel route is to be used as a washcoating step to produce thin films. 

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