Instantaneous and Complete Decomposition of Formaldehyde by Thermally Activated Oxide Semiconductors

Shima, Hideki; Takahashi, Hironori; Miyauchi, Hiroyuki; Mizuguchi, Jin

doi:10.2320/matertrans.m2011062

Cited by 10 publications

(3 citation statements)

References 21 publications

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“…4 which shows complete elimination of formaldehyde (so to speak formalin) for concentrations of 200 and 2000 ppm. 16) The experiment was performed at 500°C in air. The reaction time was calculated to be about 20 ms. Formaldehyde is extremely toxic and is classified as a cancer-causing substance.…”

Section: Introductionmentioning

confidence: 99%

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—

et al. 2015

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Thermal activation of semiconductors (TASC) is our novel technology characterized by radical propagation in giant molecules, allowing us to decompose any polymers, in an instant, into H 2 O and CO 2 . The present phenomenon has successfully been applied to complete decomposition of VOC (volatile organic compound), or to elimination of polymer matrix in composites in order to recover valuables, for example, decomposition and recovery of FRPs (fiber reinforced plastic), repair of partially damaged FRPs, reclaim of rare-earth powder from resin-bonded magnets, disassembly and recycling of solar panels and laminated glass. The TASC technology dates back to our accidental finding that significant oxidative properties appear in semiconductors when heated at about 350500°C while quite inactive at room temperature. The oxidative effect (i.e. removal of bonded electrons) has been interpreted as arising from thermally generated defect electrons ("hole") formed in the valence band of semiconductors. This triggers the decomposition of polymers by creating unstable radicals. Then, the radicals propagate, just like a domino phenomenon, throughout the polymer to make the whole polymer unstable, resulting in the fragmentation of the giant molecule into small pieces such as ethylene and propane. Finally, the fragmented molecules react with oxygen in air to give H 2 O and CO 2 (i.e. complete combustion). This process caused by radical propagation is compared to the reverse reaction of "radical polymerization". The present overview describes the recent advances in TASC technology with major focus on the disassembly and recycling of solar panels and laminated glass.

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Section: Introductionmentioning

confidence: 99%

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—

et al. 2015

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“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] This novel technology developed by us has mainly been used for complete decomposition of thermoplastic or thermosetting polymers, as well as volatile organic compounds (VOCs). However, this technology has never been tested so far for the recovery of glass fibers from FRPs.…”

Section: Introductionmentioning

confidence: 99%

Recovery of Glass Fibers from Fiber Reinforced Plastics

2011

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Recovery of glass fibers from fiber reinforced plastics (FRP) has been tackled by our novel technology based upon thermally activated semiconductors such as Cr 2 O 3 , NiO, TiO 2 , and -Fe 2 O 3 . This is a scientifically proven technology which utilizes a vast number of thermallygenerated oxidative holes for instantaneous decomposition of filler-free thermoplastic or thermosetting polymers. No shredding or grinding of the scrap FRP is necessary in the present system, nor is the use of organic solvents. FRP plates were simply placed in contact with powdered Cr 2 O 3 and heated at about 350-500 C. As soon as the FRP was sufficiently heated, the polymer matrix began to decompose into H 2 O and CO 2 , leaving behind only glass fibers without any deterioration of their quality. The glass fibers were perfectly recovered, exactly in the original form of ''chopped strand mat''. Our system can recover glass fibers as well as thermal energy.

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“…6,7) In view of the above situation, an attempt has been made in the present investigation to apply our novel technology to the present problem, utilizing thermally generated holes in semiconductors. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] The use of thermally activated holes for removal of VOC and organic wastes is an entirely new technology initiated by us in 2001. 8) The present technology uses the formation of a large number of highly oxidative holes generated by thermal excitation of semiconductors.…”

Section: Introductionmentioning

confidence: 99%

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

2011

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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.

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Instantaneous and Complete Decomposition of Formaldehyde by Thermally Activated Oxide Semiconductors

Cited by 10 publications

References 21 publications

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—

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—

Recovery of Glass Fibers from Fiber Reinforced Plastics

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

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Instantaneous and Complete Decomposition of Formaldehyde by Thermally Activated Oxide Semiconductors

Cited by 10 publications

References 21 publications

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 &mdash;A New Technology Characterized by Radical Propagation in Giant Molecules&mdash;

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 &mdash;A New Technology Characterized by Radical Propagation in Giant Molecules&mdash;

Recovery of Glass Fibers from Fiber Reinforced Plastics

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

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Product

Resources

About

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—

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—