Dehydrogenation Catalyst Activation for Benzene Purification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dehydrogenation catalysts for removing cyclohexane and methylcyclopentane impurities from benzene in hydroalkylation processes have limited activity and can undergo rapid aging, making it difficult to achieve high conversion and selectivity, especially due to the similar boiling points of these impurities and benzene.
Innovation Solution
An activation step for the dehydrogenation catalyst involving heating a catalyst precursor with 0.01 wt % to 10.0 wt % of a first metal from Groups 6 to 10 metals in a H2-containing atmosphere at 300° C. to 600° C. improves catalyst performance, achieving high conversion and selectivity without sacrificing selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dehydrogenation catalysts are used to remove cyclohexane and methylcyclopentane impurities from benzene, then the separation function is provided, but the catalyst activity is limited and rapid aging occurs, making it difficult to achieve high conversion and selectivity
Solution Approach 1:
The patent applies parameter changes by optimizing the catalyst composition parameters, specifically controlling the metal content (0.01-10.0 wt% Group 6-10 metals), metal oxide content (0.01-10.0 wt% Groups 1-3 oxides), and their ratios. The activation temperature range (300-600°C) and treatment time (0.5-10 hours) are also optimized parameters that enhance catalyst activity and stability simultaneously
Solution Approach 2:
The patent employs composite materials by combining Group 6-10 metals (Pt, Pd, Ir, Ru, Rh) with Groups 1-3 metal oxides (K2O, Na2O, CaO, MgO, Al2O3, TiO2, ZrO2, SiO2, B2O3) on an inorganic support. This composite structure creates synergistic effects where the metal provides dehydrogenation activity while the metal oxide enhances stability and resistance to aging
2Productivity
If hydroalkylation process is used to produce cyclohexylbenzene, then the desired product is formed, but cyclohexane and methylcyclopentane by-products are produced which are difficult to separate due to similar boiling points
Solution Approach 1:
The patent applies the extraction principle by using a dehydrogenation catalyst to selectively convert cyclohexane impurities back to benzene and methylcyclopentane to paraffins, effectively extracting these harmful by-products from the cyclohexylbenzene product stream. This chemical extraction approach is more effective than physical separation methods given the similar boiling points
Solution Approach 2:
The patent implements discarding and recovering by converting the unwanted cyclohexane by-product back into valuable benzene feedstock through dehydrogenation. The benzene can then be recycled to the hydroalkylation process, while the dehydrogenation by-products (hydrogen and paraffins) are either reused or discarded based on their value
3Manufacturing precision
If catalyst precursor is activated at high temperature in H2-containing atmosphere, then catalyst performance and selectivity are improved, but additional processing step and energy consumption are required
Solution Approach 1:
The patent applies preliminary action by performing activation treatment on the catalyst precursor before actual use. The catalyst is pre-treated at 300-600°C in a H2-containing atmosphere for 0.5-10 hours to reduce metal oxides to metallic state and create the active catalytic sites. This preliminary activation ensures optimal performance during subsequent dehydrogenation operations
Solution Approach 2:
The patent uses a H2-containing atmosphere during activation, which serves as a reducing environment. The hydrogen atmosphere prevents oxidation of the metal components during heating and facilitates the reduction of metal oxides to their active metallic form, creating an appropriate chemical environment for catalyst activation
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 activated catalyst demonstrates enhanced cyclohexane conversion to benzene with maintained selectivity, addressing the limitations of previous catalysts by improving dehydrogenation efficiency and stability.
Implementation Method 1
obtaining an activated dehydrogenation catalyst by treating the catalyst precursor at a temperature in a range from 300° C. to 600° C. for a period of at least 15 minutes in a H2-containing atmosphere
Implementation Method 2
contacting a first composition with the activated dehydrogenation catalyst in a dehydrogenation reactor under a dehydrogenation condition to convert at least a portion of the cyclohexane to benzene
Data Source
AI summary
Disclosed herein is a process for dehydrogenating a hydrocarbon with a dehydrogenation catalyst comprising a step of activating the catalyst precursor in a H2-containing atmosphere. A particularly advantageous activation process includes heating the catalyst precursor to a temperature in a range from 400° C. to 600° C. The process of the present disclosure is particularly advantageous for dehydrogenating cyclohexane to make benzene.