Main operating parameters of the reconditioning reaction

1. Reaction temperature

Increasing the reaction temperature is beneficial for catalyst reforming, both in terms of reaction rate and chemical equilibrium. However, the reaction temperature is also limited by the following factors：

①Materials of the equipment.

② heat stability and carbon tolerance of the catalyst.

③non-ideal side reactions; increasing the reaction temperature increases hydrocracking reactions, accelerates catalyst carbon build-up and decreases liquid yields.

④ octane number of reformed gasoline.

2. Reaction pressure

From the point of view of chemical equilibrium, increasing the reaction pressure is detrimental to the reaction of dehydrogenation of hexa-cycloalkanes and dehydrocyclisation of alkanes to produce aromatic hydrocarbons, and favours side reactions such as hydrocracking reactions. Therefore, the use of lower reaction pressure is favourable to obtain higher liquid yields and aromatic yields. At the same time, the hydrogen yield and purity are also higher.

3. Airspeed

For a given reactor, the greater the airspeed, the greater the capacity, but the shorter the reaction time and the lower the reforming rate. For the dehydrogenation of hexa-cycloalkanes, where the reaction rate is high, the effect of airspeed is not significant; for the dehydrocyclisation of alkanes, where the reaction rate is low, the effect of airspeed is more significant. For intermediate and cycloalkyl feedstocks, higher airspeeds are used, while for paraffin-based feedstocks, lower airspeeds are used.

4. Hydrogen to oil ratio

The catalytic reforming process generates hydrogen and the units all take place in a hydrogen cycle to suppress the carbon build-up on the catalyst. The hydrogen-to-oil ratio in a catalytic reforming process is the molar ratio of hydrogen in the circulating gas to the reaction feed. In the reforming reaction, in addition to the hydrogen produced by the reaction, a part of the hydrogen is mixed before the feed oil is fed into the reactor. This hydrogen is not involved in the reforming reaction and is known in industry as circulating hydrogen. The circulation of hydrogen serves the following purposes.

① diluting the feedstock, so that the feedstock is evenly distributed in the bed.

② Acts as a heat carrier, reducing the temperature drop in the bed and increasing the average temperature in the reactor.

③ Inhibit the coking reaction and protect the catalyst.

④ The addition of circulating hydrogen is an important means of regulating the hydrogen-to-oil ratio, which in turn affects the reaction pressure, which in turn plays a vital role in the reforming chemistry.