Synthesis of a New Cu-Aluminosilicate Catalyst for CO2 Capture and Conversion to Hydrocarbons

摘要

Cu-aluminosilicate has been synthesized from kaolinite through a hydrothermal reaction. The reaction conditions are 15 bar, 200°C, 9 M NaOH and a kaolinite/limestone mass ratio of 0.3 is used. This material was impregnated with copper nitrate at ambient conditions, characterized and used for CO2adsorption and conversion to hydrocarbons. X-ray diffraction analysis shows the presence of 57wt.% stilbite and 43wt.% gehlinite. Energy dispersive X-ray (EDX) proved an increase in Si/Al ratio from 0.93 to 4.3 wt.%. Also, calcium, sodium and copper oxides have increased from 0.45, 0 and 0 wt.% to 14.7,8and 2.6 wt.%, respectively. BET N2 adsorption at 77 K provided a mesoporous surface area of 6.85m~2/g and pore volume of 0.0339cm~3/g with average pore diameter of 68.9 run. This material was first tested for its adsorption capacity against CO2 in CO2/H2 mixture at different pressure and temperature values. Then it is used as a catalyst for conversion of CO2 to hydrocarbons. Adsorption isotherm shows a multilayer of coverage with a mono saturation capacity of 73.9 mg CO2/g and 34.6 mg H2/g obtained at 7bar and 250 °C. At this value a conversion of 27.6% was achieved and when total gas flow rate is20 ml/min. This value has increased to 63.9% with increasing the pressure to 50 bars. It is found that both adsorption and surface reaction control the hydrogenation of CO2 to hydrocarbon.