Organic Disulfide Catalyst Presulphidation
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Solution Overview
Problem
Current catalyst sulfurization methods for hydrotreating hydrocarbon feedstocks face challenges such as toxicity, difficulty in supplying hydrogen sulfide, and the formation of solid deposits that can lead to operational issues in industrial settings, particularly with polysulfides which decompose at lower temperatures but cause harmful blockages.
Innovation Solution
The use of diethyldisulfide (DEDS), dipropyldisulfide (DPDS), or dibutyldisulfide (DBDS) as sulfurizing agents, which decompose at lower temperatures than dimethyldisulfide, minimizing solid deposits and offering improved handling and operational safety, along with the option of incorporating odor masking agents to enhance usability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen sulfide is used as sulfurizing agent, then catalyst sulfurization is effective, but toxicity and difficulty in supplying H2S occur
Solution Approach 1:
The patent uses organic disulfides (dimethyldisulfide, diethyldisulfide, dipropyldisulfide, or dibutyldisulfide) as intermediary compounds that decompose to release hydrogen sulfide in situ. These intermediaries are less toxic and easier to handle than pure H2S, while still providing the necessary sulfurization effect through controlled decomposition at reaction temperatures.
Solution Approach 2:
The patent changes the physical and chemical parameters of the sulfurizing agent by using organic disulfides with different decomposition temperatures. Specifically, it prefers diethyldisulfide, dipropyldisulfide, or dibutyldisulfide over dimethyldisulfide because they decompose at lower temperatures, enabling sulfurization at reduced temperatures and improving safety while maintaining effectiveness.
2Temperature
If polysulfides are used as sulfurizing agent, then decomposition temperature is lower, but solid deposits and blockages occur
Solution Approach 1:
The patent carefully selects organic disulfides with specific chain lengths (methyl, ethyl, propyl, butyl groups) that decompose at optimal temperatures below 350°C but do not produce excessive solid sulfur deposits. The patent explicitly excludes polysulfides (R-Sx-R' with x≥3) and prefers compounds with x=2, balancing decomposition temperature with minimal deposit formation.
Solution Approach 2:
The patent modifies the local chemical structure by using specific alkyl groups (ethyl, propyl, butyl) attached to the disulfide bond, which changes the decomposition behavior and deposit formation characteristics compared to simpler compounds like dimethyldisulfide, achieving lower decomposition temperature without excessive solid deposits.
3Reliability
If sulfurization is carried out at high temperature, then complete sulfidation is achieved, but reduction of catalyst by hydrogen occurs
Solution Approach 1:
The patent changes the temperature parameter by using organic disulfides that decompose at lower temperatures (below 350°C, preferably below 300°C) to release H2S in situ. This allows complete catalyst sulfidation to occur at reduced temperatures where hydrogen reduction of the catalyst is minimized, while still achieving sufficient H2S concentration for effective sulfurization.
Solution Approach 2:
The organic disulfide acts as a preliminary source of H2S that decomposes before or during the sulfurization process, providing a controlled release of sulfurizing agent that maintains adequate H2S concentration at lower temperatures, preventing catalyst reduction while ensuring complete sulfidation.
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
These sulfurizing agents enable faster and more efficient catalyst sulfurization with reduced solid deposits, enhancing catalyst activity and operational safety, while maintaining high desulfurization performance comparable to dimethyldisulfide, the industry standard.
Implementation Method 1
The use of diethyldisulfide (DEDS), dipropyldisulfide (DPDS), or dibutyldisulfide (DBDS) as sulfurizing agents, which decompose at lower temperatures than dimethyldisulfide
Data Source
Figure 1
AI summary
The present invention relates to a sulphidation agent for a hydroprocessing catalyst that provides a faster sulphidation of the catalyst and also significantly reduces solid deposits, essentially sulphur. The sulphidation agent of the present invention essentially consists of diethyldisulphide (DEDS) or dipropyldisulphide(s) (DPDS) or dibutyldisulphide(s) (DBDS), and can be used in in-situ or ex-situ presulphidation methods.