The composition of hydrocracking catalyst

Hydrocracking catalyst is mainly composed of metal active component with hydrogenation and dehydrogenation function and acid carrier with cracking function. The function of these two components can be properly adjusted to meet the requirements of different cracking feedstock and products.

The main metal active components are Co, Ni, Pt, Pd, etc. The order of hydrogenation activity of these metals is:

Pt、Pd>W-Ni>Mo-Ni>Mo-Co>W-Co

Although Pt and Pd have the best hydrogenation activity, due to their high price and strong sensitivity to sulfur, they are generally only used in the second stage of the two-stage hydrocracking process, which has no sulfur and ammonia atmosphere. W, Mo and Ni are used as main catalytic metals in the catalytic cracking catalyst. For example, in the single stage hydrocracking process with middle fraction as the main product, Mo-Ni or Mo-Co catalysts are commonly used. When lubricating oil is the main product, W-Ni catalyst is often used as the main combination.

The acid component is the main source of cracking activity, and its acidity is in order of molecular sieve, amorphous silicon aluminum, alumina, and they are called acid carrier. According to their acidic structure, they can be divided into two categories: crystalline and amorphous. The former is dominated by molecular sieve, while the latter is represented by alumina and amorphous silicon and aluminum. In general, molecular sieves provide more acidic centers and stronger acidity than amorphous Si or alumina. Because of this effect, the use of molecular sieve can be appropriate to reduce the operating temperature and pressure, so that the reaction in more moderate conditions. Because the acid carrier has the function of promoting the fracture and isomerization of C-C bond, sometimes the composite acid carrier is made of molecular sieve and amorphous Si and Al. By adjusting the ratio of the two, it is suitable for the hydrocracking process of productive gasoline or productive middle distillate.