Solid Phosphoric Acid Catalyst Macropore Control
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Solution Overview
Problem
Existing solid phosphoric acid catalysts for hydrocarbon conversion processes lack sufficient porosity and stability, particularly in terms of large macropores and the ratio of silicon orthophosphate to silicon pyrophosphate, which affects their activity and longevity.
Innovation Solution
A solid phosphoric acid catalyst comprising crystalline silicon orthophosphate and optionally silicon pyrophosphate, with an integrated XRD reflectance intensity ratio of at least 5:1 and a pore volume of at least 0.17 cm3 g−1, with a significant portion contributed by macropores greater than 10,000 Å, is developed. This catalyst is manufactured through a process involving mixing phosphoric acid and a silicon source, followed by extrusion and calcination to optimize porosity and crystalline phase ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid phosphoric acid catalysts are used with traditional preparation methods, then the catalyst can be manufactured with standard porosity, but the catalyst lacks sufficient macropore volume and exhibits inadequate stability and activity
Solution Approach 1:
The patent applies parameter changes by precisely controlling the calcination temperature (400-600°C) and duration to achieve the desired crystalline phase composition (silicon orthophosphate to silicon pyrophosphate ratio of at least 5:1) and pore structure characteristics (macropore volume of at least 0.15 cm³ g⁻¹). This thermal treatment parameter optimization resolves the contradiction between manufacturing complexity and pore structure precision.
Solution Approach 2:
The patent uses composite materials by combining phosphoric acid (60-80 wt%) with siliceous materials such as kieselguhr or diatomaceous earth to create a catalyst with optimized pore structure and crystalline phase composition. The composite structure enables simultaneous achievement of high macropore volume and stable crystalline phases, resolving the reliability-manufacturing precision contradiction.
2Productivity
If the catalyst porosity is increased to improve activity, then the catalyst shows higher conversion rates, but the physical strength and structural stability may be compromised
Solution Approach 1:
The patent employs porous materials by designing a catalyst with controlled pore volume (at least 0.17 cm³ g⁻¹ total, with at least 0.15 cm³ g⁻¹ from macropores >10,000 Å) while maintaining structural integrity through the crystalline phase composition (silicon orthophosphate and silicon pyrophosphate ratio of at least 5:1). The porous structure enhances productivity while the crystalline framework preserves physical strength.
Solution Approach 2:
The composite structure of phosphoric acid combined with siliceous materials creates a catalyst that simultaneously achieves high porosity for improved conversion rates and structural stability for maintained physical strength. The siliceous framework provides mechanical support while the phosphoric acid components create the active porous sites.
3Reliability
If the calcination temperature is increased to improve crystalline phase composition, then the silicon orthophosphate to silicon pyrophosphate ratio improves, but energy consumption and manufacturing complexity increase
Solution Approach 1:
The patent optimizes the calcination temperature parameter to the range of 400-600°C, which is sufficient to achieve the desired crystalline phase composition (silicon orthophosphate to silicon pyrophosphate ratio of at least 5:1) without excessive energy consumption. This parameter optimization resolves the contradiction between improving reliability and reducing energy use.
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 improved catalyst exhibits higher activity and stability, maintaining high propylene conversion rates over extended periods, with enhanced resistance to deactivation and physical strength.
Implementation Method 1
A mixture of these two ingredients is calcined and ground down to the desired particle size
Implementation Method 2
The catalyst comprises crystalline silicon orthophosphate and, optionally, crystalline silicon pyrophosphate
Data Source
AI summary
The present invention relates to a solid phosphoric acid catalyst and a process for conversion of hydrocarbons using a solid phosphoric acid catalyst. The solid phosphoric acid catalyst comprises silicon orthophosphate, and has a silicon orthophosphate to silicon pyrophosphate ratio of at least about 5:1. The total pore volume of the solid phosphoric acid catalyst is at least about 0.17 cm3 per gram of catalyst, of which at least about 0.15 cm3 per gram is contributed by pores with diameter of at least about 10,000 Å.