Composite Hydroalkylation Catalyst for Benzene Conversion
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Solution Overview
Problem
Conventional benzene hydroalkylation catalysts suffer from low selectivity and high costs due to noble metal content, leading to economic and industrial viability issues, with complex reaction chemistry resulting in unwanted products and difficult separation of close-boiling benzene and cyclohexane.
Innovation Solution
A composite hydroalkylation catalyst is prepared through a process involving impregnation of hydrogenation metals on inorganic oxides, calcination, and integration with a molecular sieve and binder, followed by reduction and calcination, and used in a distributed feed reactor to enhance benzene conversion and yield of cyclohexylbenzene, while integrating with a catalytic reforming unit to simplify product separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hydroalkylation catalysts are used, then benzene conversion can be achieved, but selectivity for cyclohexylbenzene is low and costs are high due to noble metal content
Solution Approach 1:
The patent replaces expensive noble metal catalysts with inexpensive non-noble metal catalysts (such as nickel, cobalt, or iron) that can be easily replaced or regenerated. This substitution dramatically reduces the cost of the catalyst while maintaining acceptable catalytic activity and selectivity for cyclohexylbenzene production.
Solution Approach 2:
The patent employs composite catalyst materials combining non-noble metals with support materials (such as alumina, silica, or zeolites) to create catalysts that achieve high selectivity for cyclohexylbenzene without requiring noble metals. The composite structure allows optimization of both activity and selectivity through careful selection of metal-support combinations.
2Productivity
If conventional catalysts are used, then hydroalkylation reaction can proceed, but complex reaction chemistry results in unwanted products and difficult separation
Solution Approach 1:
The patent modifies the local chemical environment of the catalyst sites through support material selection and catalyst formulation to specifically favor the desired hydroalkylation reaction pathway. By controlling the local acidity, metal dispersion, and active site characteristics, the catalyst selectively promotes cyclohexylbenzene formation while minimizing unwanted side reactions.
Solution Approach 2:
The patent optimizes reaction parameters such as temperature, pressure, hydrogen-to-benzene ratio, and space velocity to work synergistically with the catalyst system. These parameter adjustments are tuned to maximize cyclohexylbenzene yield while minimizing the formation of unwanted products like dicyclohexylbenzene or cyclohexane.
3Quantity of substance
If benzene and cyclohexane are produced, then separation is required, but close-boiling points make separation difficult
Solution Approach 1:
The patent extracts or removes one of the separation steps from the process by designing the catalyst system to selectively produce cyclohexylbenzene without generating significant amounts of cyclohexane. This extraction of the separation function reduces process complexity and operational difficulties associated with separating close-boiling components.
4Temperature
If hydroalkylation reaction is carried out, then temperature control is challenging, but reaction efficiency is affected
Solution Approach 1:
The patent implements temperature control through feedback mechanisms including heat exchangers, temperature sensors, and automated control systems that adjust reaction conditions in real-time. The catalyst system is designed to operate within optimal temperature ranges, and any temperature deviations are automatically corrected to maintain both safety and efficiency.
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 process achieves higher selectivity and yield of cyclohexylbenzene with reduced impurities, improved temperature control, and eliminates the need for separating benzene and cyclohexane, enhancing the economic and environmental viability of the hydroalkylation process.
Implementation Method 1
Benzene is hydrogenated to cyclohexene along with little amount of cyclohexane over the metal sites of the catalyst
Implementation Method 2
Cyclohexene reacts with benzene on the acid sites of the catalyst to form the main product CHB
Implementation Method 3
effecting calcination of the metal impregnated inorganic oxide at a temperature ranging from 250° C. to 500° C. for a time period ranging from 1 hour to 15 hours
Data Source
AI summary
An aspect of the present disclosure relates to a process for preparing a composite hydroalkylation catalyst including: (a) effecting impregnation of a hydrogenation metal on an inorganic oxide to form a metal impregnated inorganic oxide; (b) effecting calcination of the metal impregnated inorganic oxide to obtain a calcined metal impregnated inorganic oxide; (c) preparing a composite mixture comprising a molecular sieve, the calcined metal impregnated inorganic oxide and a binder; (d) preparing an extruded catalyst; and (e) effecting calcination of the extruded catalyst to obtain the composite hydroalkylation catalyst. The composite hydroalkylation catalyst prepared using this process affords dramatic improvement in conversion of mononuclear aromatic hydrocarbon and the yield of the hydroalkyled mononuclear aromatic hydrocarbon (e.g. CHB).