Mild-Hydrocracking Catalyst with Balanced Acidity and Hydrogenation
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Solution Overview
Problem
Current hydroprocessing catalysts for residual oil mild-hydrocracking face challenges in achieving balanced acidity and hydrogenation functions, leading to rapid deactivation and poor selectivity for middle distillate yield due to strong acid sites and high hydrogenation activity, which affects catalyst stability and product quality.
Innovation Solution
A catalyst with a porous alumina support and a combination of Group VIII and VI transition metals, specifically NiMo or NiW, is used, which provides a balance between acidic and hydrogenation functions, maintaining activity for 200 hours with selective cracking capacity for middle distillate and naphtha, while minimizing gas formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts with strong acid sites (halogenated alumina or zeolite silica-alumina) are used, then cracking activity is improved, but catalyst deactivation occurs rapidly
Solution Approach 1:
The patent changes the acidity parameter by replacing strong acid sites (from halogenated alumina or zeolite) with weak acid sites generated by gamma-alumina support. This parameter change reduces cracking activity slightly but dramatically improves catalyst stability and resistance to deactivation, enabling sustained operation for mild-hydrocracking of residual oil
Solution Approach 2:
The patent creates a composite catalyst system combining gamma-alumina support with specific metal combinations (NiMo, NiW, CoMo, CoW) and promoters. This composite structure balances weak acid sites from gamma-alumina with hydrogenation activity from metals, achieving both stability and acceptable cracking performance
2Manufacturing precision
If high hydrogenation activity is used to improve product quality, then sulfur and nitrogen removal is enhanced, but selectivity for middle distillate decreases
Solution Approach 1:
The patent applies local quality by using specific metal combinations (NiMo, NiW, CoMo, CoW) with promoters at controlled ratios. These metals provide localized hydrogenation function for sulfur and nitrogen removal, while the gamma-alumina provides weak acid sites for controlled cracking, achieving both product quality and selectivity
Solution Approach 2:
The patent employs partial hydrogenation activity through controlled metal loading and promotion. The hydrogenation function is sufficient to remove sulfur and nitrogen effectively but not so strong as to cause excessive cracking that would reduce middle distillate yield, achieving the right balance for mild-hydrocracking
3Adaptability or versatility
If high pressure and high temperature are applied to maintain liquid yield, then process flexibility is reduced, but mild-hydrocracking can be achieved
Solution Approach 1:
The patent changes the operating parameters to milder conditions (lower pressure, moderate temperature) by using gamma-alumina supported catalysts with balanced weak acid and hydrogenation functions. This parameter change enables mild-hydrocracking to proceed effectively without requiring the extreme conditions of conventional hydrocracking, improving process flexibility
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The catalyst achieves stable performance under mild-hydrocracking conditions, enhancing middle distillate yield with simultaneous removal of sulfur, nitrogen, and metals, demonstrating improved catalyst stability and selectivity over extended time-on-stream.
Implementation Method 1
hydrocracking is a two-stage process which combines catalytic cracking and hydrogenation—where heavier feedstocks are cracked in the presence of hydrogen to produce more desirable products
Implementation Method 2
The catalytic sites, which are normally responsible for hydrogenation, can also contribute to the hydrogenolysis (C—S, C—N, C—O etc. bond breaking), where sulfur and nitrogen compounds present in the feedstock are converted to hydrogen sulfide and ammonia
Implementation Method 3
a porous alumina support and a plurality of transition metals impregnated on the alumina support. The support has a specific surface area greater than 150 m2/g, a total pore volume ranging from about 0.25 ml/g to about 1.5 ml/g
Data Source
AI summary
The catalyst for mild-hydrocracking of residual oil includes a porous alumina support a plurality of transition metals impregnated on the alumina support. The support has a specific surface area greater than 150 m2/g, a total pore volume ranging from about 0.25 ml/g to about 1.5 ml/g, about 20% of the pores having a diameter greater than 150 nm, about 70% of the pores having a diameter ranging from about 2 nm to about 150 nm, and about 10% of the pores having a diameter less than 2 nm. The plurality of transition metals include one Group VIII element and one or more Group VI elements.