Heat-Generating Inert Component for Dehydrogenation Catalyst Bed
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Solution Overview
Problem
The Houdry CATOFIN® dehydrogenation process faces challenges in maintaining a consistent temperature profile across the catalyst bed due to its adiabatic nature, leading to reduced paraffin conversion and yield, as the reaction is highly endothermic and coke distribution is difficult to control, necessitating a means to improve heat addition without catalytically active materials that produce unwanted side products.
Innovation Solution
A chromia/alumina dehydrogenation catalyst system is enhanced by physically mixing it with a heat-generating inert component, such as copper oxide supported on alumina, which is catalytically inert but generates heat during reaction conditions, matching the density and heat capacity of alpha-alumina, thereby improving heat distribution and utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If hot air is used for regeneration, then coke is removed and heat is provided, but the top of the bed becomes hotter than the bottom, creating temperature non-uniformity
Solution Approach 1:
The patent applies local quality by using two different inert materials with distinct properties: alpha-alumina (high heat capacity, high density) for the lower bed section to absorb excess heat and prevent overheating, and silica (lower heat capacity, lower density) for the upper bed section to allow adequate heat retention. This spatial differentiation of material properties creates a more uniform temperature profile throughout the catalyst bed during regeneration and dehydrogenation cycles.
2Productivity
If the dehydrogenation catalyst is used without additional heat-generating materials, then the process is simpler, but the temperature decreases by 100°C during dehydrogenation, reducing conversion
Solution Approach 1:
The patent applies preliminary action by performing oxidation of the inert materials (alpha-alumina and silica) during the regeneration step to store heat in advance. The exothermic oxidation reactions pre-heat the inert materials before the dehydrogenation step begins. When dehydrogenation occurs and the temperature would normally drop, the pre-heated inert materials release this stored heat, maintaining the temperature needed for high paraffin conversion.
3Use of energy by stationary object
If copper oxide is added as a heat-generating component, then heat is generated during reduction, but copper may participate in dehydrogenation or side reactions
Solution Approach 1:
The patent applies this principle by using copper oxide as a temporary, consumable heat-generating component that is intentionally designed to be reduced to metallic copper during the reduction step. The copper then serves as a stable, non-reactive component for the dehydrogenation step. The copper oxide is 'disposable' in the sense that it undergoes irreversible reduction to perform its heat-generating function, after which the stable copper form prevents side reactions.
Solution Approach 2:
The patent applies parameter changes by utilizing the phase transition and chemical state changes of copper species. Copper oxide (CuO) is reduced to metallic copper (Cu) during the reduction step, changing both oxidation state and chemical reactivity. This parameter change transforms the material from a heat-generating, potentially reactive state to a stable, non-reactive state that prevents side reactions during dehydrogenation.
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 introduction of the heat-generating inert component ensures improved heat management and catalyst activity, enhancing paraffin conversion and yield by maintaining a more uniform temperature profile and reducing the need for external heating, thus optimizing the dehydrogenation process.
Implementation Method 1
at least one component that is catalytically inert with respect to dehydrogenation or side reactions such as cracking or coking but that generates heat after being exposed to reducing and/or to oxidizing reaction conditions
Implementation Method 2
at least one component that is catalytically inert with respect to dehydrogenation or side reactions such as cracking or coking but that generates heat after being exposed to reducing and/or to oxidizing reaction conditions
Implementation Method 3
generates heat after being exposed to reducing and/or to oxidizing reaction conditions
Implementation Method 4
Dehydrogenation of aliphatic hydrocarbons to produce their complementary olefins is a well-known process
Implementation Method 5
The "inert" is a granular, alpha-alumina material of similar particle size to the catalyst that is catalytically inactive with respect to dehydrogenation or side reactions such as cracking or coking, but that has a high density and high heat capacity, so it can be used to store additional heat in the bed
Data Source
AI summary
An improved dehydrogenation catalyst bed system for olein production utilizing classical processing techniques is disclosed. The catalyst bed system comprises a dehydrogenation catalyst comprising an active component selected from an oxide of a metal of Group 4 or Group 5 or Group 6 and combinations thereof and a support selected from aluminum oxide, aluminas, alumina monohydrate, alumina trihydrate, alumina-silica, transition aluminas, alpha- alumina, silica, silicate, aluminates, calcined hydrotalcites, zeolites and combinations thereof mixed with a first inert material selected from any material that is catalytically inactive when subjected to reaction conditions that can effect dehydrogenation of olefins and that has a high density and high heat capacity and that is not capable of producing heat during any stage of the dehydrogenation process, and the dehydrogenation catalyst plus the first inert material then being physically mixed with a secondary component comprising a heat-generating inert material and a carrier capable of supporting the heat-generating inert material, wherein the secondary component is catalytically inert with respect to dehydrogenation reactions or to cracking or to coking and generates heat after being exposed to reducing and/or to oxidizing reaction conditions.