Complete Removal of Chloro-Based Volatile Organic Compounds by Thermally Activated Oxide Semiconductors

Abstract

Chloro-based volatile organic compounds (VOCs) are known to exert noxious effects on the environment, and their destruction by catalytic combustion, for example, accompanies a production of hydrochloric acid (HCl) that damages the catalyst. We have been interested in complete removal of VOCs by our system based on thermally activated oxide semiconductors (i.e., catalysts) such as Cr 2 O 3 , TiO 2 , NiO, -Fe 2 O 3 . In the present investigation, we have fundamentally studied the decomposition process of dichloromethane (CH 2 Cl 2 : DCM) and trichloroethylene (CHCCl 3 ; TCE) on the basis of the mass-and Raman spectra in an attempt to identify the formation temperature of HCl. Then, we found that the decomposition of DCM and TCE starts at about 100 and 200 C, respectively; whereas HCl is abruptly formed at a critical temperature of about 350 C in both compounds. Based on this result, we have optimized the operation temperature below 300 C for Cr 2 O 3 -impregnated honeycomb systems and achieved the complete removal of DCM and TCE that accompanies no formation of HCl.

Instantaneous and Complete Decomposition of Formaldehyde by Thermally Activated Oxide Semiconductors

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Our system for complete elimination of volatile organic compounds (VOCs) has the advantage of being efficient, compact and inexpensive. Our technology has been initiated by an accidental finding that oxide semiconductors such as TiO 2 exhibit no catalytic activity at room temperature, but the activity is greatly enhanced when heated at above 350-500 C. [5][6][7] The present technology uses a large number of highly oxidative holes generated by thermal excitation of semiconductors for decomposition of plastics as well as VOCs in an instant.…”

“…Our technology has been initiated by an accidental finding that oxide semiconductors such as TiO 2 exhibit no catalytic activity at room temperature, but the activity is greatly enhanced when heated at above 350-500 C. [5][6][7] The present technology uses a large number of highly oxidative holes generated by thermal excitation of semiconductors for decomposition of plastics as well as VOCs in an instant. Up to now, we have shown very successful results for complete decomposition of plastics, 6,7) volatile organic compounds, 8,11,[13][14][15]17,18,20) diesel exhausts, 8) tobacco smokes, recovery of glass fibers from fiber reinforced plastics, 21) side by side with the system development based on the fundamental elucidation of the decomposition mechanism.…”

Reclaim of Rare Earth Metals from Bond Magnets by Means of Thermally Activated Semiconductors (TASC)

“…Up to now, we have achieved complete elimination of various volatile organic compounds by TASC: toluene & benzene, 10) chloro-based organic solvents, 12) formaldehyde.…”

Recent Advances in TASC (Thermal Activation of Semi-Conductors) Technology for Environmental Issues Focused on the Disassembly and Recycling of Solar Panels and Laminated Glass —A New Technology Characterized by Radical Propagation in Giant Molecules—

“…Various VOCs were also tested: diesel exhaust, toluene, benzene and PM, 8) methanol and methane, 9) chloro-based organic solvents (dichloromethane and trichloroethlene), 15) and isopar L fluid (Exxon Mobile Chemical. ), 17) as well as ammonia, isopropyl alcohol, and tetrahydrofuran.…”