Fischer-Tropsch Catalyst Preparation via Rapid Fluidized Bed Drying
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Solution Overview
Problem
Fischer-Tropsch catalysts based on cobalt suffer from non-homogeneous cobalt distribution, leading to agglomeration and crust formation, which reduces hydrothermal resistance and selectivity in hydrocarbon synthesis reactions.
Innovation Solution
A process involving rapid drying and fluidized bed drying and calcination steps to stabilize the oxide support, facilitating the formation of a spinel phase and preventing cobalt agglomeration, resulting in a catalyst with improved hydrothermal resistance and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional drying methods are used after impregnation, then the catalyst contains residual water, but this residual water hinders homogeneous distribution of cobalt and causes agglomeration and crust formation
Solution Approach 1:
A stabilization step is performed before the main impregnation step. This preliminary stabilization creates a controlled surface environment on the oxide support that prevents cobalt agglomeration during subsequent impregnation and drying, ensuring homogeneous distribution even with residual water present
Solution Approach 2:
The patent modifies the chemical parameters of the oxide support surface through stabilization treatment, changing its affinity and interaction properties with cobalt precursors. This parameter change allows for controlled water evaporation and prevents uncontrolled cobalt migration and agglomeration
2Productivity
If cobalt content is increased to improve catalytic activity, then the catalyst becomes more sensitive to attrition and loses active metal over time, but reducing cobalt content lowers catalytic activity
Solution Approach 1:
The stabilization step creates local quality differences on the support surface, creating specific zones with enhanced cobalt anchoring properties. This local modification ensures that cobalt remains firmly attached even at high concentrations, preventing attrition-induced metal loss while maintaining high catalytic activity
Solution Approach 2:
The patent creates a composite structure where the stabilized oxide support forms a synergistic system with cobalt. The stabilization treatment modifies the support-cobalt interface, creating a composite material where cobalt is strongly anchored to the support, preventing metal loss during attrition while maintaining high activity
3Device complexity
If strong aggregation of metal occurs at the periphery of catalyst to simplify structure, then selectivity is reduced due to steric constraints limiting hydrocarbon chain growth
Solution Approach 1:
The stabilization step creates local quality variations that specifically prevent metal aggregation at the periphery while allowing controlled aggregation in the interior. This local control maintains open structures at the surface where chain growth reactions occur, preserving selectivity
Solution Approach 2:
The stabilization treatment acts as an intermediary layer between the cobalt precursor and the support surface. This intermediary controls the deposition and distribution of cobalt, preventing peripheral aggregation that would create steric constraints, while still allowing sufficient metal content for high activity
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 process achieves a homogeneous distribution of cobalt, enhancing the catalyst's hydrothermal stability and maintaining high selectivity for C5+ compounds, thereby improving the efficiency of hydrocarbon synthesis.
Implementation Method 1
a drying step in which said impregnated oxide support is entrained by means of a gas, said impregnated oxide support being subjected in said step to a temperature rise ramp of between 250 and 600°C/min
Implementation Method 2
a drying step in which said impregnated oxide support is entrained by means of a gas
Implementation Method 3
a step of calcination of said impregnated and dried oxide support, said calcination being carried out in one step, under air, at a temperature between 700 and 1200°C
Data Source
AI summary
Preparing a catalyst comprising an active phase including at least one group VIII metal consisting of cobalt, nickel, ruthenium and iron and an oxide support, comprises stabilizing the oxide support by impregnating the stabilized oxide support, drying the stabilized and impregnated oxide support in a fluidized bed using a gas for 1 second to 1 minute or 20-180 minutes and calcining the dried and impregnated oxide support, where the impregnated oxide support is subjected in the step to a temperature rise gradient of 250-600[deg] C/minutes or 0.5-5[deg] C/minutes to reach a temperature of 50-170[deg] C. Preparing a catalyst comprising an active phase including at least one group VIII metal consisting of cobalt, nickel, ruthenium and iron and an oxide support, comprises stabilizing the oxide support by impregnating the stabilized oxide support, drying the stabilized and impregnated oxide support in a fluidized bed using a gas for 1 second to 1 minute or 20-180 minutes and calcining the dried and impregnated oxide support, where the impregnated oxide support is subjected in the step to a temperature rise gradient of 250-600[deg] C/minutes or 0.5-5[deg] C/minutes to reach a temperature of 50-170[deg] C and the calcining step is carried out in two steps. An independent claim is included for Fischer-Tropsch synthesizing of hydrocarbon from a mixture of carbon and hydrogen comprising preparing the catalyst, where the Fischer-Tropsch synthesizing method is carried out at a temperature of 190-240[deg] C and a total pressure of 1-5 MPa and with a molar ratio of hydrogen/carbon monoxide is 1.5-2.5.