Hydrogenation catalyst presulfidation method

The presulfurization of hydrogenation catalyst can be divided into internal presulfurization and external presulfurization according to the way of sulfur loading. In-reactor presulfurization is presulfurization treatment after the catalyst is loaded into the reactor. There are two ways of pre-sulfurization in the container: one is to directly use a certain concentration of hydrogen sulfide in the presence of hydrogen or inject carbon disulfide or other organic sulfide into the circulating gas for vulcanization, which is called dry pre-sulfurization; the other is In the presence of hydrogen, the vulcanization is carried out with hydrocarbons or distillates containing sulfur compounds in a liquid or semi-liquid phase, which is called wet pre-sulfurization. The external pre-sulfurization technology is a process in which fresh or regenerated catalysts in an oxidized state are pre-sulfurized before being loaded into a hydrogenation unit. Using a special process, the sulfidation agent is introduced into the catalyst pores in advance, or combined with the active metal component of the catalyst in the form of a certain sulfide, the oxidized catalyst is converted into an external pre-sulfurization catalyst, there is no need to introduce sulfide after filling, so as to shorten the start-up time.

1. Internal presulfurization

So far, most manufacturers of hydrogenation catalysts still adopt the pre-sulfurization method in the tank. The vulcanizing agents they use include carbon disulfide, dimethyl disulfide, ethanethiol, thiophene, high-purity hydrogen sulfide, etc. Although the pre-sulfurization method has the advantages of simple catalyst preparation and storage, it has significant disadvantages:

(1) The system must be filled with vulcanized oil first, and then high-pressure ammonia is injected into the system, which is prone to leakage.

(2) A large amount of vulcanized oil needs to be consumed, and the follow-up treatment is very troublesome;

(3) It is easy to cause the temperature of the catalyst bed to rise sharply, resulting in catalyst sintering;

(4) The vulcanizing agent is a poisonous and harmful substance, which will endanger the health of operators and pollute the environment;

(5) Long vulcanization time will affect the normal start of work.

2. External presulfurization 

External presulfurization is the process of preparing the oxidized hydrogenation catalyst into a "presulfurization catalyst" before loading it into the hydrogenation reactor. This reaction takes a special and effective process to fully fill the sulfide into the pores of the catalyst particles, combine it with the active metal component of the catalyst in the form of a certain sulfide. Compared with internal pre-vulcanization, external pre-vulcanization has the advantages of low investment, good vulcanization effect, short start-up time, and less environmental pollution. It has been a hot research topic for scholars at home and abroad for a long time. It has a good application prospect. The method of external pre-vulcanization is the future development direction of pre-vulcanization technology, which has the advantages of simplicity, high efficiency and no pollution.