The Effect Of SO₂and Water Vapor On Activity Of Cu/γ-Al₂O₃in The Catalytic Combustion Of Ultra-low Concentration Methane

Ultra-low concentration methane is the main combustible component of coal-bedgas and industrial exhaust gas. Because of people’s low environmental consciousnessand technical limitations, ultra-low concentration methane is emitted into air withoututilization. It’s a huge waste of energy and serious air pollution. Catalytic combustion isconsidered the most effective method to utilize ultra-low concentration methane for itslow light-off temperature, high conversion rate and good thermal stability. However,ultra-low concentration methane in coal-bed gas and industrial exhaust has gaseousimpurities such as SO₂and water vapor. Gaseous impurities has low concentration butrestraining to catalytic combustion. Mechanism of sulfur poisoning in transition metalsorbent, influence of water vapor and regeneration characteristics are worthy ofstudying. Therefore, it is very meaningful to study influence of SO₂and water vapor oncatalytic combustion of ultra-low concentration methane. It has academic meaning andvalue of industrial application to analyze sulfur poisoning effect in transition metalsorbent and mechanism of water vapor.Firstly, Cu/γ-Al₂O₃particle was prepared as catalyst. Influence of roastingtemperature, capacity, reactor air speed and methane concentration were studied. Then,Experimental researches were launched on influence of SO₂and water vapor oncombustion of ultra-low concentration methane with Cu/γ-Al₂O₃catalyst. Cumulativeeffect of sulfur and ability of sulfur&water-resistance were analyzed combiningobservation of content and micro structure of catalyst. At last, mechanism of poisoningeffect in catalytic combustion was discussed. Influence of water vapor on catalyticcombustion and regeneration characteristics were studied.Results show that self-made Cu/γ-Al₂O₃catalyst is more active under roastingtemperature of600℃in this article. Activity of Cu/γ-Al₂O₃catalyst increases withdecreasing of inlet velocity and increasing of methane concentration. In the presence ofSO₂in feed gas, resulting in a poison in Cu/γ-Al₂O₃catalyst and activity of catalystdecreases with increasing of SO₂concentration. Sulfur content in Cu/γ-Al₂O₃catalystcumulates and becomes saturated with pre-sulfur time increasing. Produced sulfatedecreases active site of Cu and specific area which hinder the sorption of methanemolecule. It causes catalyst damage and decreases its activity. Water vapor existing inreaction gas also restrains activity of Cu/γ-Al₂O₃catalyst. With increasing of water vapor concentration, activity drops fast. Competitive adsorption of water vapor andmethane molecule decreases contact of methane and active sites. Meanwhile, watervapor promotes cementation of metallic oxide which decreases catalyst activity.Catalyst which reacts in atmosphere with water vapor shows better regeneration abilityin low temperature phase than high temperature phase. Stability of Cu/γ-Al₂O₃catalystdecreases with adding in SO₂and water vapor.This study analyzed mechanism of catalyst damage by SO₂and restraining effectcaused by water of Cu/γ-Al₂O₃. Study enriched theoretical basis for improvement andenhancement of sulfur and water resistance ability. And it helped the practicalengineering application of ultra-low concentration coal-bed gas.