Catalytic cracking catalyst and preparation method thereof

Abstract

The invention provides a catalytic cracking catalyst and a preparation method thereof, the catalyst is prepared from 15-60 wt% of molecular sieve, 15-60 wt% of clay, 10-30 wt% of pseudoboehmite, 5-20wt% of adhesive, 0.1-5 wt% of phosphorus-containing compound (calculated by P), 0.1-3 wt% of magnesium-containing compound (calculated by Mg), and may also contain 0-5 wt% of rare earth oxide. The preparation method comprises the following steps: (1) catalyst forming: mixing and pulping molecular sieve, clay, pseudoboehmite, phosphorus-containing compound and adhesive; then adding magnesium-containing compound to mix and pulp, heating and stirring, spraying and forming, and roasting to obtain the formed catalyst; (2) catalyst modification: mixing and pulping the formed catalyst, ammonium salt,phosphorus-containing compound and water, adjusting pH, heating and reacting, and filtering and drying to obtain the catalytic cracking catalyst of the invention. The catalytic cracking catalyst provided by the invention has the characteristics of low coke yield and high total liquid collection (liquefied gas, gasoline and diesel).

Description

technical field [0001] The invention relates to a catalytic cracking catalyst and a preparation method thereof, in particular to a phosphorus and magnesium modified catalytic cracking catalyst and a preparation method thereof. Background technique [0002] Fluid catalytic cracking technology (FCC) has become an important means of secondary processing of heavy oil due to its relatively low investment, strong feedstock adaptability, and simple operation. With the depletion of high-quality and light crude oil resources worldwide and the improvement of coking production capacity, oil refining companies have blended a large proportion of low-quality crude oil in catalytic cracking units, such as residual oil, coking wax oil, degassing oil, etc. asphalt oil etc. Due to the poor crackability of inferior feedstock oil, the amount of carbon deposited on the FCC catalyst increases, and the coke is adsorbed on the acidic center of the catalyst and is not easy to desorb, which seriousl...

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Problems solved by technology

[0016] It can be seen from the above patents that increasing the ratio of medium and large pores of the matrix material and increasing the diffusion rate of oil and gas molecules can improve the heavy oil conversion capacity and coke selectivity of the catalyst, but the improvement range is limited; and the modification of molecular sieves is the introduction of a single phosphorus element or a single magnesium element for modification

When the molecular sieve is modified with a phosphorus-containing solution, the phosphate is hydrolyzed to generate phosphoric acid, and due to the size and spatial configuration of the phosphoric acid molecule, the phosphoric acid cannot enter the pores of the molecular sieve and react with the strong acid centers in the channels [Shen Zhihong, Pan Huifang, Xu Chunsheng etc. Effect of phosphorus on surface acidity and carbon resistance of hydrocarbon catalytic cracking catalysts, Journal of Petroleum University (Natural Science Edition), 1994, 18(2): 86-99], so it cannot improve the coke selectivity of the acid center in the channel ; Magnesium ions have a small radius and can migrate into the pores of molecular sieves

However, due to the diffusion resistance of the pores, the magnesium ions will inevitably cover the outer surface of the molecular sieve and the acid centers in the large pores during the migration of magnesium ions to the pores, resulting in a decrease in the acid content of the molecular sieve and the loss of heavy oil conversion capacity.

Therefore, the above-mentioned patents cannot solve the contradiction between small-pore coke selectivity and heavy oil conversion at the same time

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