Chloride-Modified CuO Adsorbent for Benzene Saturation Sulfur Guard
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Solution Overview
Problem
Benzene saturation units in refineries face challenges with sulfur removal due to the reducibility of copper oxide (CuO) adsorbents, which leads to ineffective sulfur compound removal in mixed phase streams, causing catalyst deactivation and safety issues, and existing solutions complicate manufacturing and increase costs.
Innovation Solution
A supported CuO adsorbent with chloride addition to the copper oxide precursor or intermediate adsorbent, which increases resistance to reduction, allowing for effective sulfur removal in mixed vapor/liquid streams and maintaining the active copper phase, thereby enhancing sulfur capacity and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper oxide (CuO) adsorbent is used for sulfur removal in benzene saturation units, then sulfur compound removal effectiveness is improved, but CuO reduces to copper metal during operation causing catalyst deactivation and safety issues
Solution Approach 1:
The patent modifies the chemical composition parameters of the CuO adsorbent by adding chloride (0.1-5 wt%) and adjusting the CuO crystal structure through controlled preparation methods. This changes the reduction potential and kinetic stability of CuO, allowing it to maintain its oxidized state at operating temperatures (120-150°C) while retaining sulfur removal effectiveness. The chloride addition creates a more stable CuO phase that resists reduction to metallic copper.
Solution Approach 2:
The patent creates a composite adsorbent material combining CuO with chloride compounds (such as CuCl2 or other metal chlorides) and supports (alumina, silica). This composite structure provides synergistic effects where the chloride components stabilize the CuO phase and prevent reduction, while the support material provides mechanical strength and surface area. The composite nature allows simultaneous achievement of sulfur removal activity and reduction resistance.
2Reliability
If separate sulfur guard beds are used to achieve required sulfur removal, then sulfur outlet level is improved, but capital cost and device complexity increase
Solution Approach 1:
The patent combines the sulfur removal function and benzene saturation function into a single reactor system. The modified CuO adsorbent is placed in the same reactor as the Pt/alumina benzene saturation catalyst, eliminating the need for separate sulfur guard beds and associated heat exchangers. The chloride-stabilized CuO maintains its sulfur removal effectiveness while coexisting with the saturation catalyst, achieving functional integration that reduces capital cost and simplifies the process flow.
Solution Approach 2:
The patent creates a multi-functional adsorbent-catalyst system where the chloride-modified CuO performs dual functions: (1) sulfur removal through chemisorption on CuO surfaces, and (2) protection of the Pt catalyst by maintaining low sulfur levels. The single integrated bed serves multiple purposes that previously required separate units, making the system more efficient and cost-effective.
3Quantity of substance
If CuO is used for sulfur adsorption in mixed phase streams, then sulfur removal capacity is improved, but CuO reduces rapidly producing excessive moisture and exotherm
Solution Approach 1:
The patent changes the thermodynamic and kinetic parameters of the CuO reduction reaction by adding chloride modifiers. This shifts the reduction temperature range to higher values and reduces the rate of reduction at operating temperatures (120-150°C). The chloride-stabilized CuO maintains its sulfur adsorption capacity while producing significantly less water and heat during operation, eliminating the harmful exotherm and moisture generation problems.
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 chloride-modified CuO adsorbent significantly improves sulfur removal efficiency, extends catalyst service life, reduces water production, and avoids exothermic reactions, resulting in a more cost-effective and safer sulfur guard product capable of treating mixed phase streams.
Implementation Method 1
A supported CuO adsorbent with chloride addition to the copper oxide precursor or intermediate adsorbent, which increases resistance to reduction, allowing for effective sulfur removal in mixed vapor/liquid streams
Implementation Method 2
the CuO reduces to a lower valence state, at the typical operating temperatures in the range of ambient temperature for a make-up hydrogen treater and 120° to 150° C. for liquids being treated
Implementation Method 3
since the reduction process is highly exothermic, when used in connection with gases that have a low specific heat, the temperature exotherm can result in unsafe conditions
Data Source
AI summary
The service life and deactivation rate of a benzene saturation catalyst is improved through use of a new sulfur guard bed containing a chloride additive. This sulfur guard bed, which contains supported CuO material having an increased resistance to reduction, shows such improvement. Thus, the danger of run-away reduction followed by a massive release of water and deactivation of an isomerization catalyst is practically eliminated. The fact that the guard bed material preserves the active metal phase-copper in an active (oxide) form is an important advantage leading to very low sulfur content in the product stream. The sulfur capacity per unit weight of sorbent is also significantly increased, making this sorbent a superior cost effective sulfur guard product. The guard bed is effective in treating mixed phase feed streams.