Pre-sulfiding Residuum Hydroconversion Catalysts
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Solution Overview
Problem
Existing hydroconversion catalysts face premature deactivation due to coking mechanisms in high-severity environments, leading to reduced hydrocarbon conversion and frequent catalyst change-outs, and current pre-treatment methods require toxic sulfur-containing compounds, increasing operational costs and complexity.
Innovation Solution
Concurrent pre-sulfiding and pre-conditioning of hydroconversion catalysts using residuum hydrocarbon feedstocks with sulfur-containing compounds, converting metal oxides to passive sulfide forms, reducing carbon deposition and thermal shock susceptibility, and eliminating the need for external sulfur-containing compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fresh hydroconversion catalyst is used in high-severity environment, then high reaction rates and hydrocarbon conversion are achieved, but premature deactivation occurs due to thermal shock and excessive coking
Solution Approach 1:
The catalyst is pre-sulfided and pre-conditioned before entering the high-severity hydroconversion reactor. This preliminary treatment converts metal oxides to sulfide forms and creates a protective carbon layer, preventing thermal shock and excessive coking when the catalyst first contacts the high-severity environment, thereby maintaining both high reaction rates and catalyst stability
Solution Approach 2:
A protective carbon layer is formed on the catalyst surface through pre-conditioning with hydrocarbon feedstock before the catalyst enters the high-severity environment. This carbon layer acts as a cushion that reduces thermal shock and prevents direct contact between the fresh catalyst and aggressive conditions, thereby preventing premature deactivation while maintaining catalytic activity
2Reliability
If traditional pre-sulfiding methods using elemental sulfur or sulfur-containing compounds are employed, then catalyst sulfiding is achieved, but equipment complexity and operational costs increase due to storage, feeding, and separation requirements
Solution Approach 1:
The hydrocarbon feedstock itself serves as the sulfur source for pre-sulfiding the catalyst. The sulfur contained in the feedstock automatically sulfides the catalyst as it passes through the pre-conditioning zone, eliminating the need for separate sulfur storage, handling, and injection equipment, thereby reducing equipment complexity while achieving adequate catalyst sulfiding
Solution Approach 2:
The hydrocarbon feedstock performs multiple functions: it serves as the process feed, the sulfur source for catalyst pre-sulfiding, and the conditioning agent for forming the protective carbon layer. This multi-functionality eliminates the need for separate sulfur-containing compounds and their associated handling equipment, reducing both capital and operating expenses
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 catalyst activity and cycle time, reduces coking rates, and lowers operational costs by using in-situ hydrocarbons for pre-treatment, minimizing equipment needs and safety risks, while maintaining reactor performance with continuous catalyst transfer.
Implementation Method 1
Hydrogen is then used as a reducing agent to convert the elemental sulfur to hydrogen sulfide in situ
Implementation Method 2
converting metal oxides to passive sulfide forms
Data Source
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AI summary
A hydroconversion process is disclosed, including contacting of hydrogen and a residuum hydrocarbon with a pre-conditioned and at least partially sulfided hydroconversion catalyst for converting at least a portion of the residuum hydrocarbon into at least one of a hydrotreated product and a hydrocracked product. Pre-sulf?ding and preconditioning of the catalyst may include: intermittently or continuously: feeding a hydroconversion catalyst comprising a metal oxide to a pre-reactor; feeding hydrogen and the residuum hydrocarbon comprising sulfur-containing compounds to the pre-reactor; contacting the hydroconversion catalyst with hydrogen and the sulfur-containing compounds in the pre- reactor at conditions of temperature and pressure to concurrently: i) convert at least a portion of the metal oxide to a metal sulfide; and ii) pre-condition the catalyst; recovering a residuum hydrocarbon having a reduced sulfur content from the pre-reactor; and transporting the preconditioned and at least partially sulfided hydroconversion catalyst from the pre-reactor to the ebullated-bed hydroconversion reactor.