Spinel Chromium Dehydrogenation Catalyst for Stable Fluidized Beds
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Solution Overview
Problem
Existing fluidized bed dehydrogenation catalysts suffer from insufficient strength, abrasion, and stability, leading to high catalyst consumption and equipment requirements, with low propane conversion rate and propylene yield.
Innovation Solution
A light alkane chromium-based dehydrogenation catalyst with a spinel structure, comprising specific promoters and a fluidized bed carrier, is developed to enhance stability and abrasion resistance, featuring a preparation method involving impregnation, aging, drying, and calcination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional chromium-based catalysts use aluminum oxide as carrier and add alkali metals to reduce acidity, then the catalyst acidity is reduced, but the catalyst stability deteriorates
Solution Approach 1:
The patent changes the carrier material from aluminum oxide to silica, and adjusts the promoter composition to include alkali earth metals (Ca, Mg, Sr, Ba) combined with transition metals (Fe, Cu, Zn, Ga, In, La). This parameter change in carrier and promoter composition achieves both reduced acidity and improved stability through the formation of stable spinel structures.
Solution Approach 2:
The patent creates a composite catalyst material combining silica carrier with multiple promoters including alkali earth metals and transition metals. This composite structure forms stable spinel phases that simultaneously reduce acidity and enhance catalyst stability, resolving the contradiction between acidity reduction and stability maintenance.
2Object-affected harmful factors
If alkali earth elements are added to dehydrogenation catalyst to cover acidic sites and improve selectivity, then the catalyst selectivity is improved, but the service life deteriorates because the alkaline earth element does not form a spinel structure with the carrier
Solution Approach 1:
The patent changes the carrier from aluminum oxide to silica, which enables the formation of stable spinel structures with alkali earth metal promoters. This parameter change allows the alkaline earth elements to form stable spinel phases with the carrier, simultaneously achieving improved selectivity and extended service life.
Solution Approach 2:
The patent develops a composite catalyst system using silica carrier combined with alkali earth metals and transition metals that forms stable spinel structures. This composite material architecture enables both selectivity improvement through acidic site coverage and service life extension through stable spinel formation, resolving the previous contradiction.
3Productivity
If fluidized bed reactors are used for alkane dehydrogenation to achieve continuous reaction and regeneration, then the production continuity is improved, but the catalyst abrasion and strength requirements increase
Solution Approach 1:
The patent creates a composite catalyst material with silica carrier and multiple promoters that forms stable spinel structures. This composite structure enhances catalyst mechanical strength and abrasion resistance, enabling the catalyst to withstand the harsh conditions of fluidized bed reactors while maintaining continuous production capability.
Solution Approach 2:
The patent changes the carrier material to silica and adjusts the promoter composition to include alkali earth metals with transition metals, forming stable spinel phases. This parameter change improves catalyst strength and abrasion resistance, allowing the catalyst to survive fluidized bed operation without excessive wear while maintaining continuous production.
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 exhibits higher dehydrogenation activity, propylene selectivity, and stability, reducing catalyst loss and enhancing the efficiency of fluidized bed reactors.
Implementation Method 1
a light alkane chromium-based dehydrogenation catalyst... dehydrogenation of alkanes to olefins
Implementation Method 2
the catalyst has a spinel structure... the alkaline earth element forms a spinel structure with the carrier
Implementation Method 3
preparation method involving impregnation, aging, drying, and calcination
Implementation Method 4
preparation method involving impregnation, aging, drying, and calcination
Data Source
AI summary
The present invention discloses a light alkane chromium-based dehydrogenation catalyst, and a preparation method and application thereof, and belongs to the field of petrochemical technology. The dehydrogenation catalyst has a spinel structure and comprises the following components in mass fractions based on the total weight on a dry basis: 0.1-35% of chromium oxide, 0.1-5% of a first promoter, 0.1-10% of a second promoter, 0.1-5% of a third promoter, and the balance being a fluidized bed carrier. This dehydrogenation catalyst controls the existence state of the active centers in the catalyst by adjusting the electrical properties of the surface of the carrier, resulting in higher dehydrogenation activity and propylene selectivity of the catalyst; at the same time, it enhances the overall stability, strength, and attrition of the catalyst, alleviating the loss problem of the catalyst during use.