Kinetic laws of dimethyl ether synthesis in synthesis gas

CuO*ZnO*Al2O3*ZrO2/HSZ and Cr2O3*ZnO*Al2O3/HSZ catalysts with high activity of the following composition were used for methanol synthesis. Preliminary catalytic experiments showed that a 1:1 ratio of CuO*ZnO*Al2O3*ZrO2/HSZ:Cr2O3*ZnO*Al2O is acceptable. The amount of substances leaving the reactor was analyzed chromatographically. Two flow devices were used to conduct catalytic experiments: in the pressure range of 2– 4 MPa and in the range of 0.2–0.6 MPa (low pressure device). The inner diameter of the reactor is 11 mm and the outer diameter of the thermocouple channel is 4 mm. Catalyst weighing 0.5 g, fraction 0.25-0.315 mm was used. Catalyst activation was carried out in a nitrogen-hydrogen stream (≈2 volume.%Н2at N2, flow rate ≈2 l/h). Synthesis gas composition in catalytic experiments, volume.%: СО – 21,8; СО2 – 5,2; N2 – 5,3: H2 – 67,7. The contact time, kgcat·h/l, was determined by the formula: r=3600m/Vкир, the conversion of methanol to DME was determined by the formula: ХСН3ОН=2СDME·100(2СDME+См). As the contact time increases (decrease in volumetric velocity), the conversion of methanol to DME increases as the thermodynamic equilibrium value approaches. A decrease in pressure leads to a decrease in the rate of methanol formation, but does not affect methanol dehydration. Therefore, the lower the pressure during the same contact, the higher the methanol synthesis. It should be noted that the presence of methanol in the reaction products occurs with the thermodynamics of the dehydration reaction. Selection of conditions for direct synthesis allows to change the DME: methanol interaction ratio.