Comparison table of existing two-step dimethyl ether technologies

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| Serial Number | Comparison Item | Liquid-phase composite acid catalysis method (A) (this technology) | Gas-phase two-step method (B) | Danish Topsφe (C) | Japanese Toyo (D) |
| --- | --- | --- | --- | --- | --- |
| 1 | Production method | Methanol via liquid-phase catalytic dehydration | Syngas via gas-phase catalytic dehydration | Methanol via gas-phase catalytic dehydration | Methanol via gas-phase catalytic dehydration |
| 2 | Catalyst | Liquid-phase composite acid | γ-Al2O3 | γ-Al2O3 | γ-Al2O3 |
| 3 | Catalyst price | Low | High | High | High |
| 4 | Raw material consumption | 1.40 tons per ton of dimethyl ether | 1.80 tons per ton of dimethyl ether | 2.0 tons per ton of dimethyl ether | 1.80 tons per ton of dimethyl ether |
| 5 | Reactor structure | Single-stage liquid catalyst, uniform temperature rise, simple structure | | | |The one-pass conversion rate of methanol is high; the selectivity for dehydration is good. In the multi-stage cooling type, the temperature rise is moderate. The one-pass conversion rate of methanol is average, and the selectivity for dehydration is also average in the adiabatic type, with the highest temperature rise – this affects the methanol conversion rate, while the selectivity for dehydration is low in the heat-exchange type. It is similar to option (B), but requires higher investment. 5. The raw material is crude methanol; no concentration is needed for the crude methanol. Concentration is required, and energy consumption is high. 5. The raw material vaporizes, and a direct liquid-liquid reaction takes place between the raw material and the catalyst, so vaporization is not necessary. Partial vaporization results in high steam consumption. Complete vaporization; high steam consumption. Complete vaporization; high steam consumption. 6 Unreacted methanol: the one-pass conversion rate of methanol recovery is greater than 93%, while the methanol recovery rate is low. It can significantly reduce energy consumption and investment costs. The one-way conversion rate of methanol is less than 80%; a large amount of methanol is recovered, requiring the addition of a methanol stripping tower for dimethyl ether recovery, and steam energy consumption is high. A methanol concentration tower is used for distillation-based concentration and recovery. There are costs associated with the investment in methanol concentration towers and their supporting equipment, as well as steam energy consumption. A methanol concentration tower is used for distillation-based concentration and recovery. There are costs associated with the investment in methanol concentration towers and their supporting equipment, as well as steam energy consumption. 7. For the reaction off-gases, absorption is not required as they only need to be separated; however, since these off-gases carry a large amount of methanol, the methanol solution resulting from absorption must be stripped, which increases energy consumption. The reaction off-gases carry away a large amount of methanol; the methanol obtained after absorption requires further distillation, which increases energy consumption. Same as (C). Industrialization time: 1994, 1995, 2003; pilot plant capacity of 50 Kg/d – no commercial plant yet built. In 2004, Lutianhua built the first industrial plant. Industrial production capacity and technical maturity: 30,000 tons/year – mature; 10,000 tons/year – mature; 10,000 tons/year – immature; 10,000 tons/year – fairly mature. Capacity of plants under construction: 200,000 tons/year, 100,000 tons/year, 100,000 tons/year. Investment: 100% (baseline), 1.25, 2.0, 1.5. Process technology advancement: most advanced among existing industrial plants; high consumption levels. Technical costs: none, 6 million yuan, >15 million yuan, 15 million yuan