III International Conference

PP-III-42CATALYTIC METHODS FOR CLEANUP OF GASES FROM COAL THERMALCONVERSION PROCESSES FOR SUBSEQUENT APPLICATION IN POWER ANDCHEMICAL INDUSTRIESKundo N.N., Kovalenko O.N., Faddeenkova G.A.Boreskov Institute of Catalysis SB RAS, Novosibirsk, RussiaE-mail: oven@catalysis.nsk.suThe problem of exhausting deposits of oil and natural gas is leading to increased interestin coal as a source of heat, electricity and feedstock for chemical processes. Gaseous productsof coal coking and gasification are readily transportable, promising for chemical synthesis andprovide highly efficient heat conversion to electricity. However, the gases contain highboilingunstable admixtures and corrosive compounds, such as hydrogen sulfide and hydrogencyanide. To make the gases acceptable for use in compressors and to meet strict ecologicalstandards, the content of H 2 S and HCN in the gases must be reduced to ~20 ppmV. Themethod of aqueous alkaline oxidative absorption at ambient temperature is quite acceptablefor this purpose. The solution absorbs heavy compounds and resins, while H 2 S, HCN andNH 3 are bound chemically into nonvolatile safe compounds. The key process of this methodis the oxidation of the absorbed H 2 S to sulfur and ammonium thiosulphate by air. Thereaction of hydrogen cyanide with polysulphides – an intermediate product of H 2 S oxidation –yields ammonium thiocyanate, excessive H 2 S gives sulfur and ammonium thiosulphate. Thesecompounds are commercially valuable and can be utilized.Based on the screening of catalysts for H 2 S oxidation in solutions, a catalyst was selectedcontaining cobalt phthalocyanine derivatives. The catalyst performance exceeds by severalorders of magnitude that characteristic of other catalysts (salts and complexes of transitionmetals and quinones). Specific feature of cobalt phthalocyanine derivative determining itsunique catalytic behavior consists in the formation during catalytic reaction of the redoxspecies containing Co with oxidation degrees 2, 3 and 1, as well as CoPc complexes withmolecular oxygen. The reactions of H 2 S and HCN binding are accompanied by alteration ofCo oxidation degree. Experimental tests proved high efficiency of H 2 S and HCN removalfrom the coke gases.Realization of this gas purification scheme will allow more efficient conversion of gascombustion heat in a gas-turbine power plant with down-stream utilization of the spent gas548