Pillared Clay as an Effective Catalyst for Low Temperature VOCs Decomposition

Volatile organic compounds (VOCs) are organic chemicals mostly emitted from different sources like industrial or domestic having high vapor pressure at room-temperature conditions. Some of these are also anthropogenic in nature and also these are the major contributor for the photochemical ozone. The different methods available for the abatement of VOCs are thermal oxidation, catalytic oxidation, photocatalytic oxidation, adsorption etc. Due to the stringent regulation of VOCs emission in different countries there is a need of efficient abatement technology to preserve the environment. In this context catalytic combustion of organic pollutants offers considerable advantages over the industrially operated thermal combustion process. Generally, oxidative destruction is possible at low temperature in presence of a catalyst. In addition catalytic process is more energy efficient and can operate with very dilute pollutants. A number of catalysts have been used for the complete oxidation of VOCs, among these Pillared clays type porous materials are also useful for the purpose. Pillared clays have high surface area, pore volume, thermal stability and can be tailor made for particular catalytic application compared with the parent clays. In the present review we will summarize the latest developments on the clay based materials including the effect of different controlling parameters for the synthesis of pillared clay based porous materials and its specific application for the low temperature VOCs decomposition. In particular the effect of transition metals like iron and manganese oxide pillared clay on the VOC decomposition is discussed.

Nonthermal Plasma Hybrid Technology for VOCs Decomposition

Because of its wide pollution, large flow and low concentration, the waste gas containing volatile organic compound (VOCs) will be controlled more strictly on its emission, and new technologies for its treatment must be developed continuously. As an emerging technology for environmental protection, non-thermal plasma (NTP) has been subjected to extensive researches over the past 20 years. In the field of air pollution control, the NTP technology has been used for the abatement of various types of hazardous air pollutants due to its unique properties including the moderate operation conditions (normal temperature and atmospheric pressure), moderate capital cost, compact system, easy operations and short residence times, compared to the conventional technologies. Especially, combined plasma technology has multi-function effects, better pollutant degradation efficiency, better energy utilization efficiency and higher pollutant selectivity than single plasma technology. The research progresses in treatment of waste gas containing VOCs and the patents application by plasma technology combined with adsorbent, catalyst and ferroelectric are summarized and analyzed. From the review, we can come to a conclusion the synergistic technology result in greater enhancement of VOCs decomposition and energy efficiency. The development direction of combined plasma technology is prospected.

VOCs Decomposition Using Multiple Catalysis in Non-Thermal Plasma Processing

A series of experiments were performed for toluene removal from a gaseous influent at normal temperature and atmospheric pressure by adsorption & non-thermal plasma strength & nano-catalysis technology. Non-thermal plasma was generated by dielectric barrier discharge. Sorbent & nano-catalyst were called combined catalyst which included MnO2/γ-Al2O3 and nano-Ba0.8Sr0.2Zr0.1Ti0.9O3 catalyst. MnO2/γ-Al2O3 has an advantage for ozone removal, while nano-Ba0.8Sr0.2Zr0.1Ti0.9O3 is a kind of good material for improving energy utilize rate. The results showed the synergistic technology resulted in greater enhancement of toluene removal efficiency and energy efficiency and a better inhibition for O3 formation in the gas exhaust. Based on data analysis of FT-IR, the experiment discussed decomposition mechanism and reaction process of toluene. The results showed that synergic effect could control byproducts effectively.

Design of a Novel Corona Plasma Reactor for Decomposition of VOCs

The configuration of discharge electrode is closely related to the uniformity and the strength of corona plasma, which has big effect on the efficiency of plasma in destructing pollutants, treating materials and so on. A novel sheet electrode was devised to enhance the input energy and the uniformity of plasma’s distribution, and its production performance of plasma was compared with other discharge electrodes including wire, needle and multi-needles. Corona images and I-V characteristic curves of discharge electrodes indicate that ultra-thin sheet electrode could produce more uniform and stronger corona plasma zone than other electrodes in this paper, which is advantageous for decomposing pollutants, treating material surface and so on. Primary VOCs decomposition experiments were conducted, and the results indicated that the highest energy yield of VOCs decomposition reached 1.8 g (benzene) • (kWh)-1 /3.5 g (toluene) • (kWh)-1.