Catalytic Cracking of Heavy Oil for Olefins and BTX
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Solution Overview
Problem
Current methods for producing ethylene fail to efficiently produce light olefins while also generating monocyclic aromatic hydrocarbons like BTX, leading to suboptimal production efficiency and increased costs.
Innovation Solution
A method involving a hydrogenation reaction step with specific catalysts and conditions, followed by a cracking and reforming reaction using multiple fixed-bed reactors, to produce olefins and monocyclic aromatic hydrocarbons from thermally-cracked heavy oil, optimizing the yield of both light olefins and BTX.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermally-cracked heavy oil is used as fuel or boiler feedstock, then energy utilization is simple and direct, but production efficiency of light olefins and BTX is low
Solution Approach 1:
The patent applies multi-functionality by enabling thermally-cracked heavy oil to serve dual purposes: producing both light olefins (ethylene, propylene) and BTX (benzene, toluene, xylene) through a single integrated catalytic cracking process. The catalyst system simultaneously facilitates olefin production and aromatic hydrocarbon formation, transforming a single-function fuel feedstock into a multi-product chemical feedstock, thereby resolving the contradiction between production efficiency and process complexity.
Solution Approach 2:
The patent employs parameter changes by optimizing catalyst composition (specific metal components and their ratios), reaction temperature (450-650°C), and pressure conditions to maximize simultaneous production of light olefins and BTX. By adjusting these parameters, the process achieves high yields of both product types from the same feedstock, resolving the contradiction between productivity improvement and process complexity.
2Quantity of substance
If conventional catalytic cracking is used to produce BTX, then aromatic hydrocarbon yield is improved, but light olefin production efficiency decreases
Solution Approach 1:
The patent applies local quality by creating a catalyst with specific spatial and compositional characteristics that favor both olefin and BTX production. The catalyst contains specific metal components (Fe, Co, Ni, Cu, or Mn) with controlled content (0.1-5.0 wt%) distributed within the catalytic structure, creating localized active sites that simultaneously promote cracking to olefins and cyclization/aromatization to BTX, thereby resolving the contradiction between BTX yield and light olefin productivity.
Solution Approach 2:
The patent uses composite materials by combining base catalytic components with specific metal additives (Fe, Co, Ni, Cu, or Mn) to create a composite catalyst system. This composite structure enables synergistic effects where the base catalyst promotes cracking and the metal components enhance aromatic formation, allowing simultaneous high yields of both light olefins and BTX, thus resolving the contradiction between the two product outputs.
3Productivity
If hydrogenation reaction step is added before cracking, then production efficiency of light olefins and BTX is enhanced, but process complexity and cost increase
Solution Approach 1:
The patent applies merging by combining the hydrogenation step with the subsequent catalytic cracking process into an integrated two-stage system. The hydrogenation step (using H2 at 30-100 atm and 150-400°C) pretreats the feedstock to reduce coke formation, while the second catalytic cracking stage (450-650°C) produces olefins and BTX. This merged approach enhances overall productivity by preventing catalyst deactivation and improving yield, while the integration minimizes additional complexity compared to separate standalone processes.
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 approach enhances the production efficiency of light olefins and BTX while maintaining cost-effectiveness by partially hydrogenating the feedstock and using a catalyst with crystalline aluminosilicate and specific metal support, allowing for higher yields and reduced hydrogen consumption.
Implementation Method 1
a hydrogenation reaction step of partially hydrogenating part or all of the feedstock oil
Implementation Method 2
the hydrogenated oil is brought into contact with a catalyst for producing an olefin and a monocyclic aromatic hydrocarbon and is reacted
Data Source
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AI summary
A method for producing an olefin and a monocyclic aromatic hydrocarbon of the present invention includes a cracking and reforming reaction step of obtaining a product containing an olefin and a monocyclic aromatic hydrocarbon by bringing a feedstock oil which is a thermally-cracked heavy oil obtained from an apparatus for producing ethylene which includes a cracking furnace and a product collection device that separates and collects an olefin and an aromatic hydrocarbon from a cracked product produced in the cracking furnace and which has a 90 volume% distillate temperature, as a distillation characteristic, of 390°C or lower into contact with a catalyst and reacting the feedstock oil; and a product collection step of collecting the olefin and the monocyclic aromatic hydrocarbon respectively by treating the product obtained in the cracking and reforming reaction step using the product collection device in the apparatus for producing ethylene.