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The reduction characteristic of methanol-to-hydrogen catalysts is rapid speed and ease of reduction; practical experience shows that when the inlet temperature is 160°C and the hydrogen concentration entering the tower is 1.0%–1.2%, over 90% of the hydrogen can be consumed； Therefore, the catalyst can carry out the reduction reaction at low temperatures with a lower hydrogen concentration. (1) After confirming that the O2 content in the carrier gas is less than 0.2%, the hydrogen blending test can be carried out. This test can be performed at 160°C, as the hydrogen consumption reaction is significant at this temperature. The hydrogen blending valve should be opened slowly; by examining the relationship between the degree of opening of this valve and the concentration, it is also possible to check whether the entire hydrogen blending system and analysis system are functioning correctly. (2) The reduction rate at the reduction temperature increases as the temperature rises; increasing the temperature and concentration makes it difficult to control the temperature rise in the catalyst bed. Since the reduction reaction of CuO in the catalyst is significant at 160°C, this temperature is maintained while gradually increasing the hydrogen concentration. (3) Under reduced-pressure conditions, the hydrogen partial pressure is high, the reaction rate is fast, and it is difficult to control the temperature. Therefore, the reduction pressure is usually kept below 0.5 Mpa, and a Roots blower with a pressure of 0.049 Mpa is generally used as the circulation pump. The inlet of the Roots blower is connected to the outlet of the gas-liquid separator; air, H2, and N2 can be fed into the main inlet pipe as heating or reducing agents. In this case, N2 is used directly as the heating and reducing gas. The outlet is connected to a heat exchanger, thus forming a closed loop. During the reduction process, H2 is continuously consumed and needs to be replenished. (4) The reduction reaction of the catalyst at a hydrogen concentration is a highly exothermic reaction; therefore, it must be carried out at low hydrogen concentrations. Based on the temperature rise, the inlet temperature is maintained at a level that facilitates efficient reduction. The hydrogen concentration is gradually increased from 0.2%, 0.4%, 0.6% until it stabilizes around 2%. An analysis of hydrogen consumption is conducted later on, and only when the theoretical hydrogen consumption of the catalyst exceeds 80% can the hydrogen concentration be raised above 2%. (5) Space velocity (carrier gas flow rate): The level of space velocity has a direct impact on the rate of reduction. When the hydrogen concentration remains constant, increasing the space velocity accelerates catalyst reduction, and it is also easier to carry away the heat generated. Where conditions permit, a higher space velocity should be used as much as possible. Under normal conditions, the reduction space velocity is 200–400 h-1; users can choose an appropriate space velocity based on actual circumstances, as too low a linear velocity can lead to flow deviation. (6) Initial reduction stage (induction period): The hydrogen concentration during the initial reduction stage can be maintained at 0.2–0.8%. After hydrogen addition, the hydrogen content at the inlet and outlet is analyzed once; under normal circumstances, this analysis is carried out every half hour to monitor hydrogen consumption promptly and to observe the temperature rise in the bed and hydrogen consumption levels. Key points to note at this stage: Hydrogen blending is carried out at 160°C (the temperature of the heat transfer oil inlet unit), and there may be a certain induction period during reduction. (7) Principles for the reduction main stage>: increase temperature without increasing hydrogen flow, increase hydrogen flow without increasing temperature; add hydrogen in small amounts but frequently, conduct analyses regularly, and operate under conditions of high space velocity, low temperature, low hydrogen concentration, and low pressure as much as possible. ‚If the inlet temperature of the bed layer remains stable at 160°C and the peak temperature in the bed layer is below 220°C, the hydrogen concentration can be increased gradually, with an increase of 0.2% each time. The hydrogen content at both the inlet and outlet should be analyzed after each increase to verify that the hydrogen concentration has indeed risen. It is necessary to wait half an hour for stability after adding hydrogen before increasing it again; at all times, it must be ensured that no temperature point exceeds 230°C. ③Once the hydrogen content in the inlet reaches 2.0%, the hydrogen concentration cannot be increased any further, and operation must be maintained at this concentration. ④A small amount of CO2 is generated during the reduction process; when the CO2 content in the recycle gas exceeds 15%, nitrogen must be added and vented to reduce the CO2 level. When reduction enters the main phase, with the oil temperature in the reactor at 200°C, the hydrogen concentration can be gradually increased to 1.0%–2.0%, depending on the temperature rise. Key points to note at this stage: keep hydrogen consumption below 2% to prevent hydrogen accumulation, which could cause overheating ； Once the temperature starts to rise, it is necessary to cool down promptly, reduce the concentration of incoming hydrogen, or cut off the hydrogen supply; if needed, increase the amount of nitrogen to lower the temperature. (8) At the end of the reduction stage, there is still a certain amount of hydrogen consumption. It is necessary to monitor the progress of reduction based on various data and phenomena such as hydrogen consumption, so as to have a clear understanding of the situation; one should not rush, as this could lead to misjudgments and overheating. At this point, the temperatures at various points in the bed gradually become uniform, with only the temperature at the bottom remaining high. The inlet temperature can be increased at a rate of 2–5°C/h until it reaches 220°C, ensuring that the hottest spot in the bed does not exceed 230°C. Key points to note at this stage: There is still some hydrogen consumption during this period, and ensure that no hot spots exceed 230°C. (9) During the reduction test period, if there is no significant temperature rise in the bed layer and the hydrogen concentrations at the inlet and outlet show little difference, the hydrogen concentration supplied should be increased gradually (at a rate of 1.0% per hour), along with the inlet temperature; this process should be repeated until the hydrogen content reaches 20%, the inlet temperature of the bed layer reaches 220°C, and after maintaining this temperature for 3 hours, no significant difference is observed between the hydrogen concentrations at the inlet and outlet – at this point, the reduction process is complete. If a sudden rise in temperature or signs of overheating are detected during the process, the hydrogen supply should be cut off immediately, and more nitrogen should be introduced to purge the area and lower the temperature. Key points to note at this stage: When the hydrogen consumption gradually decreases to around 0.2%, the oil temperature can first be raised to 230°C–240°C; at this point, hydrogen consumption may increase again. If the temperature rise is not significant, the hydrogen concentration can be gradually increased from 2% to 20%. If there is no sign of an increase in the temperature of the catalyst bed, and the hydrogen levels at the inlet and outlet remain the same, it indicates that the reduction process of the catalyst is complete, and the catalyst is ready for use in production.