Composite Sorbent for HCl Removal from Hydrocarbon Streams
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Solution Overview
Problem
Existing sorbents for removing HCl from hydrocarbon streams, such as alumina-based materials, have limited chloride loading capacity, tend to form 'green oils' that foul the sorbent bed, and are not regenerable, leading to premature sorbent failure and environmental disposal issues.
Innovation Solution
A composite sorbent process involving a mixture of alumina powder and sodium sesquicarbonate, with optional sodium acetate, that reacts to form Dawsonite crystals, enhancing chloride loading capacity and mechanical stability while maintaining low reactivity and porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alumina-based sorbents are used to remove HCl from hydrocarbon streams, then HCl removal is achieved, but the sorbent has limited chloride loading capacity and forms green oils that foul the sorbent bed
Solution Approach 1:
The patent employs a composite sorbent material consisting of alumina combined with alkali metal oxides (such as sodium oxide or potassium oxide) and optionally zinc oxide. This composite structure enables the sorbent to achieve high chloride loading capacity (exceeding 20 wt-%) while the alkali metal components suppress the formation of green oils by neutralizing acidic sites on the alumina surface that would otherwise catalyze hydrocarbon polymerization.
2Quantity of substance
If promoters such as sodium carbonate or sodium hydroxide are added to alumina to increase HCl sorption capacity, then sorption capacity increases, but the sorbent becomes less stable and more difficult to handle
Solution Approach 1:
The patent optimizes the composition parameters by controlling the weight percentages of each component: alumina (50-90 wt-%), alkali metal oxides (5-30 wt-%), and optionally zinc oxide (0-20 wt-%). This parameter optimization ensures high HCl sorption capacity while maintaining sorbent stability and handling characteristics. The controlled composition prevents excessive reactivity that would compromise reliability.
Solution Approach 2:
By creating a composite material with balanced composition ratios, the patent achieves both high sorption capacity and operational stability. The synergistic combination of alumina (providing structural framework), alkali metal oxides (providing high capacity chloride binding sites), and optional zinc oxide (enhancing stability) resolves the contradiction between capacity and reliability.
3Reliability
If the sorbent bed is changed frequently due to premature failure, then HCl removal efficiency is maintained, but production time is lost and disposal costs increase
Solution Approach 1:
The patent enables continuous operation by providing a sorbent with extended service life that maintains high HCl removal efficiency throughout its operational period. The improved sorbent composition prevents premature failure and green oil fouling, allowing uninterrupted hydrocarbon stream treatment and eliminating the need for frequent bed changes, thereby maintaining continuous production without downtime.
4Quantity of substance
If alumina-based sorbents are used, then HCl removal is achieved, but the sorbent is not regenerable and requires disposal
Solution Approach 1:
The patent enables sorbent regeneration by providing a composite material that can be thermally treated to remove absorbed HCl and restore its sorption capacity. The alkali metal-containing composite structure allows for regeneration through controlled heating that decomposes chloride salts back to oxides and HCl gas, which can be removed. This regeneration capability eliminates the need for frequent disposal and reduces environmental harm, while maintaining effective HCl removal capability across multiple cycles.
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 composite sorbent achieves high dynamic capacity for HCl removal with reduced 'green oil' formation, improved mechanical stability, and lower reactivity, extending sorbent life and reducing disposal costs.
Implementation Method 1
A composite sorbent process involving a mixture of alumina powder and sodium sesquicarbonate, with optional sodium acetate, that reacts to form Dawsonite crystals
Implementation Method 2
The composite sorbent achieves high dynamic capacity for HCl removal
Data Source
AI summary
A composite sorbent is formed which is the reaction product of a solid alkali metal carbonate, rehydratable alumina and water or an aqueous solution of a metal salt. The reaction between the components occurs while forming particulates followed by curing and activation. In one embodiment, the composite contains an appreciable amount of a Dawsonite-type hydroxycarbonate as a final product or as an intermediate in at least one of the production stages. The alkali metal in the sorbent exhibits a highly reactive and accessible state that is very favorable for various sorption applications. The sorbent is especially useful for removal of HCl and other acid contaminants from gas and liquid hydrocarbon streams. It combines a high capacity for the contaminants with a low reactivity towards the hydrocarbon components of the main stream.