Alkylbenzene Refining System Heat Duty Reduction via Transalkylation

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Solution Overview

Problem

Current solid catalytic processes for producing detergent-range alkylbenzenes face challenges in energy efficiency and selectivity, requiring high benzene to olefin ratios which increase energy costs and result in the formation of undesirable byproducts, while also posing operational hazards due to the use of hydrogen fluoride.

Innovation Solution

The process involves alkylation with a low benzene to olefin ratio followed by transalkylation to enhance energy efficiency and product quality, using a solid, acidic catalyst to produce alkylbenzenes with reduced heat duty in the refining system and improved selectivity, allowing for the conversion of dialkylbenzenes to monoalkylbenzenes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a high benzene to olefin ratio is used in alkylation, then selectivity to alkylbenzene is improved, but energy consumption in the refining system increases

Engineering Contradiction:

Improveselectivity to alkylbenzeneVSAvoidenergy consumption in refining system

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The process is divided into two distinct stages: alkylation stage where benzene reacts with olefin to form alkylbenzene and dialkylbenzene, followed by a transalkylation stage where dialkylbenzene is converted back to alkylbenzene. This segmentation allows optimization of each stage independently, using lower benzene to olefin ratio in alkylation while maintaining overall selectivity through the transalkylation step.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the operational parameters by introducing a transalkylation step with specific temperature and catalyst conditions. This parameter change enables the system to operate with lower benzene to olefin ratios in the alkylation stage while still achieving high alkylbenzene selectivity through the subsequent transalkylation conversion of dialkylbenzene.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If a low benzene to olefin ratio is used in alkylation, then energy consumption is reduced, but formation of byproducts increases

Engineering Contradiction:

Improveenergy consumptionVSAvoidformation of byproducts

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful byproduct dialkylbenzene (formed in lower benzene to olefin ratio alkylation) into a beneficial resource by subjecting it to transalkylation. This transalkylation process converts the unwanted dialkylbenzene back into desired alkylbenzene product, thereby transforming the harmful byproduct formation into a beneficial outcome that maintains product quality while using lower benzene to olefin ratios.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If hydrogen fluoride is used as catalyst, then alkylation efficiency is improved, but operational hazards increase

Engineering Contradiction:

Improvealkylation efficiencyVSAvoidoperational hazards

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the hazardous hydrogen fluoride catalyst with alternative solid acid catalysts that are safer and more environmentally friendly. This substitution maintains alkylation efficiency while eliminating the operational hazards associated with hydrogen fluoride, aligning with the principle of replacing harmful substances with safer alternatives.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 reduces energy consumption in the alkylbenzene refining system, maintains product quality, and mitigates the use of hazardous chemicals by improving the selectivity and efficiency of alkylbenzene production while allowing for the use of sulfur-containing paraffin feedstocks.

Implementation Method 1

The catalysts are not selective and other reactions of olefins can occur to produce heavies, i.e., dimers and dialkylaryl compounds. Also, skeletal isomerization of the olefin can occur

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

The distillation to separate alkylbenzene from heavies, including dialkylbenzene, is typically conducted under subatmospheric pressure and is energy intensive to maximize the recovery of alkylbenzene

Methodology Applied

Scientific EffectDistillation: Distillation

Implementation Method 3

a transalkylation of dialkylbenzene co-produced during alkylation is used to reduce energy costs per unit of alkylbenzene product

Methodology Applied

Scientific EffectTransalkylation: Chemical Bonding

Data Source

PatentUS7642389B2Energy integrated processes including alkylation and transalkylation for making detergent range alkylbenzenes

Publication Date: 2010.01.05 UOP LLC

AI summary

Integrated, energy efficient process for making detergent range alkylbenzenes use a combination of a low benzene to olefin feed ratio for alkylation, alkylbenzene refining system operation and a transalkylation of dialkylbenzene co-produced during alkylation is used to reduce energy costs per unit of alkylbenzene product.