A hydrogen production unit that directly feeds natural gas to reduce the conversion system, and incorporates a desulfurization system into it?
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What are the implications of incorporating the desulfurization system into the system as well? Why does it need to be restored every time work starts?
Use natural gas for reduction? Is that true? The purity of hydrogen obtained from natural gas can reach that of reducing hydrogen; natural gas serves as a raw material, thus it counts as an input
Having a desulfurization system doesn’t have much impact; it is usually installed only at the time of initial operation. Under normal operating conditions, nitrogen is used, but when production stops, oxygen present in the nitrogen can oxidize part of the catalyst or cause oxidation due to air infiltration, so reduction is necessary to enhance the catalyst’s activity
It depends on the sulfur content in the raw material; if the sulfur content is low, it can be directly reduced using natural gas, without the need to add hydrogen
It’s related to the catalyst, I guess. But under normal circumstances, the hydrodesulfurization system is a single unit; even if some components of the feed gas do not contain sulfur, it’s only the hydrogenation unit that is separated from the rest – there’s no reason to separate the desulfurization unit.
The main thing to consider are impurities such as toxins in natural gas; if the raw material is of good quality, it’s possible to proceed with direct reduction. Nowadays, many refineries use direct reduction with natural gas
Can natural gas reduce and transform catalysts? It is only known that some hydrogenation catalysts do not require pre-sulfurization; they can be fed directly with the feedstock and undergo sulfurization gradually during the production process
First, the reduction may not be complete; second, the subsequent process stages need to be separated to prevent catalyst poisoning
The conversion catalyst possesses a certain level of activity before it is reduced, so it is possible to use sulfur-free natural gas directly. At first, the amount of natural gas used should be as small as possible to facilitate hydrogen production; as the amount of hydrogen increases, the catalyst begins to be reduced gradually. Of course, this process will result in slight carbon buildup, but it has little impact on the catalyst.
The role of a catalyst is to accelerate the reaction rate and shorten the reaction time; it does not participate in the reaction itself； Moreover, in many hydrogen production processes, there is no H2 or ammonia available before operation begins; therefore, CH4 is used to reduce the catalyst. However, the reaction rate is slow and the conversion efficiency is low at the initial stage, so a high water-to-carbon ratio must be used for catalyst reduction.