BTX Production via Layered Catalyst Reforming and Hydrocracking
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Solution Overview
Problem
Current processes for producing BTX from C5-C12 hydrocarbon mixtures result in low yields and produce significant amounts of side products of lesser value, requiring solvent extraction and high fuel gas consumption, with hydrocracking further reducing aromatic production and increasing hydrogen consumption.
Innovation Solution
A process involving a single reactor with a layered catalyst system, where a reforming catalyst dehydrogenates naphthenes to aromatics, followed by a hydrocracking catalyst that cracks paraffinic and olefinic co-boilers to produce high-value LPG, allowing for solvent-free BTX separation by distillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If catalytic reforming is used to produce BTX from C5-C12 hydrocarbon mixture, then BTX is obtained, but side products of C5 to C10 non-aromatic species are produced which require further solvent extraction processing
Solution Approach 1:
The patent combines catalytic reforming and hydrocracking functions into a single integrated process using a bifunctional catalyst. The reforming function converts naphthenes to aromatics (BTX), while the hydrocracking function simultaneously cracks paraffinic and olefinic co-boilers. This merging eliminates the need for separate solvent extraction units and produces high-value LPG as a useful byproduct, thereby reducing process complexity while maintaining or improving BTX production efficiency
2Quantity of substance
If hydrocracking is used to convert naphtha, then LPG is produced, but the amount of BTX produced is not high and hydrogen consumption increases
Solution Approach 1:
The patent applies local quality by using a bifunctional catalyst with distinct reforming and hydrocracking sites. The reforming function specifically targets naphthenes to convert them to aromatics (BTX), while the hydrocracking function selectively cracks paraffinic and olefinic co-boilers. This localized functional differentiation ensures that naphthenes are converted to BTX rather than being cracked, thereby maintaining high BTX yields while producing valuable LPG from the co-boilers and reducing unnecessary hydrogen consumption
3Quantity of substance
If previous processes are used to convert hydrocarbon feedstock, then aromatic compounds are produced, but non-aromatic hydrocarbons co-boil with BTX requiring solvent extraction and fuel gas is produced at the expense of LPG
Solution Approach 1:
The patent converts the harmful effect of co-boiling non-aromatic hydrocarbons with BTX into a benefit by using the hydrocracking function to selectively crack these co-boilers into lighter, high-value LPG products. This approach eliminates the separation difficulty by transforming the problematic co-boiling components into desirable products, thereby simplifying the separation process and eliminating the need for solvent extraction while producing additional valuable LPG
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
This process enhances BTX yield, reduces cracking severity on hydrocracking catalysts, and produces valuable LPG as side products, achieving longer catalyst cycle lengths and lower capital expenditures while producing chemical-grade BTX without solvent extraction.
Implementation Method 1
Use of the reforming catalyst has the effect of dehydrogenating cyclohexane to benzene and methyl cyclohexane to toluene etc. The majority of the C6-C8 naphthenes in the feedstream are thus upgraded to the corresponding C6-C8 aromatics.
Implementation Method 2
the reformed product stream is contacted in the presence of hydrogen with a hydrocracking catalyst to produce a hydrocracking product stream comprising BTX. During hydrocracking the reformed product stream is converted to the hydrocracking product stream that comprises hydrocarbon products with a lower amount of carbon atoms (lighter products).
Implementation Method 3
The BTX is subsequently separated from the hydrocracking product stream. This separation can be performed by methods known to a person skilled in the art, for example by distillation.
Data Source
AI summary
The invention relates to a process for producing BTX comprising: (a) contacting a feedstream comprising C5-C12 hydrocarbons in the presence of hydrogen with a reforming catalyst to produce a reformed product stream, wherein the reforming catalyst comprises a hydrogenation metal and a support of an amorphous alumina, (b) contacting the reformed product stream in the presence of hydrogen with a hydrocracking catalyst to produce a hydrocracking product stream comprising BTX, wherein the hydrocracking catalyst comprises a hydrogenation metal and a zeolite and (c) separating the BTX from the hydrocracking product stream, wherein the hydrocracking catalyst comprises 0.01 -1 wt%, preferably 0.01 -0.5 wt%, of the hydrogenation metal in relation to the total catalyst weight and the zeolite has a pore size of 5-8 A and a silica (SiO2) to alumina (AI2O3) molar ratio of 5-200, preferably 30-120, wherein step (b) or steps (a) and (b)_are performed at a temperature of 425-580 °C, a pressure of 300-5000 kPa gauge and a Weight Hourly Space Velocity of 0.1 -15 h-1 preferably 0.1 -10 h-1.