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Natural-gas-run buses in Gothenburg
N12
Catrlytic Destruction of Haiogenated Volatile Organic Compounds Haiogenated volatrle organic compounds (VOCs) are associated wrth a broad range of rndustnal processes When released ~rttothe atmosphere these consttute a major source of arr pollutron Recognrtron of the damaging effects of these emissrons on the envrronment IS leading to Increased demands for their control While platinum metals are most effective for the catalyttc destruction of non-halogenated VOCs, little IS publrshed on their behavrour for haiogenated VOC destruction in a recent article by H Wrndawrand M Wyatt (Platinum Metals Rev, 37 (1993) 166), the authors report on the performance of platinum metal catalysts for the destruohon of haiogenated VOCs Catalytlc Incineration IS investigated in view of the potential technological and economrc advantages rt provides compared to thermal combustion systems, wrth carbon droxide, water and hydrogen halides being the desrred combustron products Catalysts are prepared by deposrtion of the piatrnum component onto a washcoat layer on a ceramic honeycomb support, aged at temperatures above 600°C for 165 hours in a chlorinated hydrocarbon gas atream containing air and moisture Using light off curves the authors show the oxrdatron of saturated Cg compounds to occur more readily than for C1 and for the reaction to be insensitive to the chlorine carbon ratio in the molecule for both C, and Cp compounds For unsaturated compounds oxidation IS more drffrcult which IS in contrast to non-halogenated hydrocarbons and these UnSatUrated compounds may be generated by the rapid oxidation of saturated compounds at low temperatures
applied catalysis 8. Environmental
By examining concentration effscts they suggest that increasing the concentration of unsaturated halocarbons whether as the primary pollutant or byproduct of incomplete combustion may require relatively higher temperatures, but these are still well below those for thermal destruction Results from concentratron effects, oxygen effects and water effects (steam) are used to support the conclusion that the mechanism of destruction IS likely to be controlled by removal of halide from the catalyst surface and not the drssocratrvechemrsorptronof the halocarbon as IS thought to occur wrth the catalytic oxidation of hydrocarbons Excess steam IS also effective In suppressing the formation of phosgene, an unwanted by product of the destruction process A number of ways in which the durability of these catalysts may be affected are put forward High durabrktyfor platinum group metals IS currently being observed in field trials in conclusion, results of ongoing field trials show catalytic processes to Offer both economic and technical advantages over established incineration methods MICHAEL McGRATH
Natural-Gas-Run Buses in Gothenburg
In a previous article in News Brief (Appl Catal 60 (1992) N4) Menon reported on “Ethanol-Run Buses in Stockholm” In Gothenburg, the second largest city of Sweden, a fleet test IS now going on wdh twenty Volvo buses which run on natural gas The motrvations for this test are low price and ready avarlabrirtyof natural gas, low exhaust and noise levels, open experiment in the midst of the public in crowded parts of the crty, and the tremendous PRvalue of eco-friendly or “green” buses Volume 3 No 2-3 -
1 February 1664
N13
One of the main objectrves ISto develop a bus with exhaust emrssrons as low as those from passenger cars fitted wrth three-way exhaust catalysts The twenty Gothenburg buses have altogether covered over 866,666 km In the crty centre and other busy areas Their diesel engines have been converted to operate accordrng to the Otto pnncrple These lean-burn engines run at arr/fuel ratros (n) of 1 4-l 6 (4969% excess of air) The cylrnder heads, pistons and camshafts have been attered and the volumetnc compressron ratro has been rarsed to 12 7 The spark plugs are changed every 26,996 km The Volvo engines are addrtronaliy equipped wrth a surveillance and engine diagnosis system The North Sea natural gas, brought by pipeline to Gothenburg, contains 91% methane, 5% ethane, 18% propane, 1% C4’s, and 0 8% CO* This gas IS stored in high pressure tanks on the roof of the bus (reducing the passenger load from the normat 78 to 68) Each bus has 15 tanks, each of 86 dm3 (hence a total tank volume of 1 2 m”) filled at 209 bar pressure The tanks are made of steel, alumrnium, or composites The dnvrng range wrth one full tank-load IS 500 km, which IS enough for Inner-crty operation These buses are fitted wrth exhaust oxidation catalysts on metal-monokth substrates The emissions In g/kWhfrom these natural-gas buses, according to the stationary test procedure ECE R49, are methane 1 8, NMHC (non-methane hydrocarbons) 0 2, NO, 2 0, CO 0 3, and panaulates 005 The Gothenburg Transport authontres feel that the fleet-test results so far are qurte posttrve Srmilar fleet tests wrth natural gas are also now going on at Malmo in the southern part of Sweden and at Trondheim on the west coast of Norway
applied catalysis B. Environmental
In the Norrkopng-Lnkoplng area on the Swedish east coast, another fleet test IS operating wrth buses run on biogas L PElTERSSON and P G MENON New Materials for VOC Destructlon New materials are being developed for the destruction of volatile organic compounds (VOCs) A catalyst/reactant has been developed by Berty Beaction Engrneers, Ltd (Fogelsvrlle, PA) to oxidize the halogenated organics and srmuttaneousiy capturethe halogensfromlhe off-gas This novel material results In no gaseous HCI or Cln In contrast, conventional catalysts used for VOC oxidation generate gaseous HCI and/or Cl0 that can suppress catalytic acttvlty, corrode equipment, and require a separate scrubber for removing these acid gases The material developed by Betty contains copper and manganese oxide supported on sodium carbonate The metal oxides catalyze the oxidation of chlonnated organics and react wrth chlorine to form metal chlorides The metal chlorides then react with sodium carbonate resutting in the formation of NaCl and COn Once the sodium carbonate support IS used up, the cataly.st/reactant can be reclaimed by drssolvrng the salt and reusing the metals Laboratory experiments have shown that 99% conversion of the VOC can be achieved in the 270°C to 400°C temperature range and 6,766 h-’ space velocrty For example, wrth 31 ppm tnchloroethylene FCE), 99% conversron level IS reached at 270°C Some diphloromethane IS formed as a by-product, Its concentration IS maximum at 240°C’ and becomes negligible at 468’C
Volume 3 No 2-3 -
1 February 1994
Catrlytic Destruction of Haiogenated Volatile Organic Compounds Haiogenated volatrle organic compounds (VOCs) are associated wrth a broad range of rndustnal processes When released ~rttothe atmosphere these consttute a major source of arr pollutron Recognrtron of the damaging effects of these emissrons on the envrronment IS leading to Increased demands for their control While platinum metals are most effective for the catalyttc destruction of non-halogenated VOCs, little IS publrshed on their behavrour for haiogenated VOC destruction in a recent article by H Wrndawrand M Wyatt (Platinum Metals Rev, 37 (1993) 166), the authors report on the performance of platinum metal catalysts for the destruohon of haiogenated VOCs Catalytlc Incineration IS investigated in view of the potential technological and economrc advantages rt provides compared to thermal combustion systems, wrth carbon droxide, water and hydrogen halides being the desrred combustron products Catalysts are prepared by deposrtion of the piatrnum component onto a washcoat layer on a ceramic honeycomb support, aged at temperatures above 600°C for 165 hours in a chlorinated hydrocarbon gas atream containing air and moisture Using light off curves the authors show the oxrdatron of saturated Cg compounds to occur more readily than for C1 and for the reaction to be insensitive to the chlorine carbon ratio in the molecule for both C, and Cp compounds For unsaturated compounds oxidation IS more drffrcult which IS in contrast to non-halogenated hydrocarbons and these UnSatUrated compounds may be generated by the rapid oxidation of saturated compounds at low temperatures
applied catalysis 8. Environmental
By examining concentration effscts they suggest that increasing the concentration of unsaturated halocarbons whether as the primary pollutant or byproduct of incomplete combustion may require relatively higher temperatures, but these are still well below those for thermal destruction Results from concentratron effects, oxygen effects and water effects (steam) are used to support the conclusion that the mechanism of destruction IS likely to be controlled by removal of halide from the catalyst surface and not the drssocratrvechemrsorptronof the halocarbon as IS thought to occur wrth the catalytic oxidation of hydrocarbons Excess steam IS also effective In suppressing the formation of phosgene, an unwanted by product of the destruction process A number of ways in which the durability of these catalysts may be affected are put forward High durabrktyfor platinum group metals IS currently being observed in field trials in conclusion, results of ongoing field trials show catalytic processes to Offer both economic and technical advantages over established incineration methods MICHAEL McGRATH
Natural-Gas-Run Buses in Gothenburg
In a previous article in News Brief (Appl Catal 60 (1992) N4) Menon reported on “Ethanol-Run Buses in Stockholm” In Gothenburg, the second largest city of Sweden, a fleet test IS now going on wdh twenty Volvo buses which run on natural gas The motrvations for this test are low price and ready avarlabrirtyof natural gas, low exhaust and noise levels, open experiment in the midst of the public in crowded parts of the crty, and the tremendous PRvalue of eco-friendly or “green” buses Volume 3 No 2-3 -
1 February 1664
N13
One of the main objectrves ISto develop a bus with exhaust emrssrons as low as those from passenger cars fitted wrth three-way exhaust catalysts The twenty Gothenburg buses have altogether covered over 866,666 km In the crty centre and other busy areas Their diesel engines have been converted to operate accordrng to the Otto pnncrple These lean-burn engines run at arr/fuel ratros (n) of 1 4-l 6 (4969% excess of air) The cylrnder heads, pistons and camshafts have been attered and the volumetnc compressron ratro has been rarsed to 12 7 The spark plugs are changed every 26,996 km The Volvo engines are addrtronaliy equipped wrth a surveillance and engine diagnosis system The North Sea natural gas, brought by pipeline to Gothenburg, contains 91% methane, 5% ethane, 18% propane, 1% C4’s, and 0 8% CO* This gas IS stored in high pressure tanks on the roof of the bus (reducing the passenger load from the normat 78 to 68) Each bus has 15 tanks, each of 86 dm3 (hence a total tank volume of 1 2 m”) filled at 209 bar pressure The tanks are made of steel, alumrnium, or composites The dnvrng range wrth one full tank-load IS 500 km, which IS enough for Inner-crty operation These buses are fitted wrth exhaust oxidation catalysts on metal-monokth substrates The emissions In g/kWhfrom these natural-gas buses, according to the stationary test procedure ECE R49, are methane 1 8, NMHC (non-methane hydrocarbons) 0 2, NO, 2 0, CO 0 3, and panaulates 005 The Gothenburg Transport authontres feel that the fleet-test results so far are qurte posttrve Srmilar fleet tests wrth natural gas are also now going on at Malmo in the southern part of Sweden and at Trondheim on the west coast of Norway
applied catalysis B. Environmental
In the Norrkopng-Lnkoplng area on the Swedish east coast, another fleet test IS operating wrth buses run on biogas L PElTERSSON and P G MENON New Materials for VOC Destructlon New materials are being developed for the destruction of volatile organic compounds (VOCs) A catalyst/reactant has been developed by Berty Beaction Engrneers, Ltd (Fogelsvrlle, PA) to oxidize the halogenated organics and srmuttaneousiy capturethe halogensfromlhe off-gas This novel material results In no gaseous HCI or Cln In contrast, conventional catalysts used for VOC oxidation generate gaseous HCI and/or Cl0 that can suppress catalytic acttvlty, corrode equipment, and require a separate scrubber for removing these acid gases The material developed by Betty contains copper and manganese oxide supported on sodium carbonate The metal oxides catalyze the oxidation of chlonnated organics and react wrth chlorine to form metal chlorides The metal chlorides then react with sodium carbonate resutting in the formation of NaCl and COn Once the sodium carbonate support IS used up, the cataly.st/reactant can be reclaimed by drssolvrng the salt and reusing the metals Laboratory experiments have shown that 99% conversion of the VOC can be achieved in the 270°C to 400°C temperature range and 6,766 h-’ space velocrty For example, wrth 31 ppm tnchloroethylene FCE), 99% conversron level IS reached at 270°C Some diphloromethane IS formed as a by-product, Its concentration IS maximum at 240°C’ and becomes negligible at 468’C
Volume 3 No 2-3 -
1 February 1994