Methanol to hydrogen

Why do some devices use acidic water?

Use pure water; conductivity requirements apply. Water and methanol enter the converter to react, as not all of the reactants involved in the chemical reaction are converted. The small amount of unconverted water remaining after the reaction is the acidic water. It is then mixed with feed water before entering the converter. Recycle and reuse to save energy and reduce consumption.

Desalinated water is used primarily to remove chloride ions, in order to prevent catalyst poisoning.

One batch of desalinated water, that is, one batch of RO product water

Deionized water – Specifications for deionized water: Conductivity 0.2 μs/cm (at 25°C); pH value 6–7; Silica content ≤0.02 mg/l; Chlorides ≤100 ppb; Copper content ≤0.2 ppm; Iron content ≤0.3 ppm; Sulfur content ≤60 ppb; Total solids ≤5 ppm

Use reverse osmosis water~~The water quality requirements are chloride levels below 1 mg/L and conductivity below 10 us/cm~~

Regarding the water quality requirements for hydrogen production from methanol, the people upstairs have already given the answers. The most important factor is the chloride ion content, as its main purpose is to prevent catalyst poisoning. The process involves washing with water from a purification tower after water cooling; the reflux liquid is acidic water. This water is reused in the process, and upon depressurization, a large amount of carbon dioxide is released. When mixed with methanol, carbon dioxide is released again from the reflux liquid, but not all of it can be extracted. The carbon dioxide that remains enters the system to participate in reactions, and this does no harm to the catalyst. If the oxygen content requirement for the product gas is very strict (for example, oxygen < 2 PPm), the deionized water entering the purification tower needs to have its dissolved oxygen removed. Of course, it is possible to add deoxygenation adsorbents to the PSA adsorbents, but this increases the cost and thus the overall investment expense.