|
With the recent emergence of energy use global tensions and exacerbate the problem of environmental pollution as a \With other DME synthesis process compared to one-step synthesis of dimethyl ether technical process is simple, less equipment, low investment, low operating costs, so that the DME production costs are reduced, economic efficiency is improved, is a prospect broad DME production technology. This paper studies a high performance bifunctional catalyst for the goal, first launched on the one-step synthesis of DME Catalyst. In Cu-Zn-Al-Li as a catalyst for methanol synthesis catalyst and methanol dehydration catalyst HZSM-5 complex, composed of dual-function catalyst was studied Cu-Zn-Al-Li/HZSM-5 bifunctional catalyst performance, study its step DME synthesis activity and stability, on the basis of the preparation method on Cu-Zn-Al-Li/HZSM-5 bifunctional catalyst performance, the final effect on the reaction conditions were analyzed. Studies show Cu-Zn-Al/HZSM-5 bifunctional catalyst, methanol synthesis component is added after Li, Cu-Zn-Al-Li/HZSM-5 bifunctional catalytic performance is greatly improved , CO conversion was 57.3%, DME selectivity of 65.68%, DME space-time yield of 0.228 g-DME/g-cat/h, were increased by 137%, 2.2% and 22%; compared with the mechanical mixing of Prepared Cu-Zn-Al-Li/HZSM-5 deposition precipitation higher catalytic performance, one-step synthesis of dimethyl ether reaction x CO, S 2, STY increases in both. At 533K, 4.0MPa, 3000h-1 under the conditions, CO conversion rate reached 88.9%, DME space-time yield of 0.404g-DME/g-cat/h; under certain reaction conditions, the reaction temperature was increased, CO conversion rate, DME DME selectivity and space-time yield rate first increased and then decreased, one-step synthesis of dimethyl ether has an optimal activity of the reaction temperature; under certain reaction conditions, as the pressure increases, CO conversion and DME space time yield rate has increased significantly, while the DME selectivity increased slightly; under certain reaction conditions, when the space velocity from 2500h-1 starts to increase, CO conversion, DME and DME space time yield selectivity decreased rate . The XRD analysis showed that before the reaction, after the reaction of CuO bifunctional catalyst surface active component content is reduced, HZSM-5 zeolite crystal phase does not change significantly, so bifunctional catalyst deactivation is mainly methanol synthesis component decrease in active ingredient content of CuO. Based on the study of the catalyst, combined with laboratory data obtained using Aspen Plus process simulation software for one-step synthesis of DME process conducted a preliminary simulations. Through an annual output of 100,000 tons of DME demonstration project preliminary design and simple calculations, the following conclusions: (1) isolated by DME and methanol products. DME product flow is 262.700kmol / h, the purity was 99.8% (mass concentration) of DME recovery of 96.4%; methanol products flow of 10.800 kmol / h, a purity of 99.6% (mass concentration), the recovery of pure methanol 96.3%. (2) the use of energy Aspen Plus simulation results, calculate the energy requirements of the process. Throughout the one-step synthesis of DME process, the need to provide heat 83314.88MJ / h, providing cold energy 36544.98MJ / h, cooling water is 56.94t / h. (3) for the one-step synthesis of DME process has been optimized in the energy calculation, the process unit operations in the heat released is used to heat the unit operations required. After optimization, the process does not require additional supply of heat, greatly reduces the energy supply. (4) In the one-step synthesis of dimethyl ether in the process of the separation section, the top of the absorber B4 gas products - stream 7 contains a large amount of H2, CO and other flammable gases, can be directly fed into the gas turbine to generate electricity. Calculated generating capacity of 43kW.
|