Cobalt Catalyst on Mesoporous Zirconia-Alumina Carrier for Kerosene Synthesis
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Solution Overview
Problem
Conventional catalysts for Fischer-Tropsch synthesis have high investment and operation costs, produce excessive methane due to strongly acidic sites, and exhibit weak isomerization performance, resulting in low iso-alkane content in gasoline and diesel fractions, limiting their fuel oil quality and low-temperature flowability.
Innovation Solution
A catalyst carrier comprising mesoporous zirconia, silicoaluminophosphate molecular sieve, modified Al-SBA-16, sesbania gum powder, and alumina, with a soluble cobalt salt loaded on the surface, which reduces methane production and enhances isomerization performance, allowing for selective synthesis of high-quality kerosene fractions from syngas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional catalysts with strongly acidic sites (molecular sieves ZSM, Y, MOR or activated carbon) are used, then catalyst activity is improved, but excessive secondary cleavage occurs producing more methane and iso-alkane content remains low
Solution Approach 1:
The patent uses a composite carrier combining mesoporous silica (SBA-15 or SBA-16) with modified alumina. The mesoporous silica provides high surface area and pore structure for catalyst dispersion, while the modified alumina component introduces moderate acidity and isomerization activity. This composite structure avoids the excessive acidity of conventional molecular sieves, reducing methane production while enhancing iso-alkane formation through isomerization reactions.
Solution Approach 2:
The patent modifies the acidity parameter of the carrier by treating alumina with specific chemicals or controlling its preparation conditions to achieve moderate acidity. This parameter change transforms the carrier from strongly acidic (conventional molecular sieves) to moderately acidic, which suppresses excessive secondary cleavage and methane production while maintaining sufficient catalytic activity and introducing isomerization capability.
2Power
If carbon material carriers are used to attenuate interaction between active component and carrier, then catalyst activity is improved, but isomerization performance remains very weak resulting in low iso-alkane content
Solution Approach 1:
The patent creates a composite carrier by combining mesoporous silica with modified alumina. The mesoporous silica component provides the high surface area and pore structure for good catalyst dispersion and activity, while the modified alumina component contributes moderate acidity and isomerization performance. This composite approach integrates the advantages of both materials, achieving both high catalyst activity and good isomerization capability.
Solution Approach 2:
The modified alumina component serves multiple functions: it provides structural support, contributes to catalyst dispersion, and most importantly, introduces isomerization activity through its moderate acidity. This multi-functional design allows the carrier to not only support the active cobalt component for Fischer-Tropsch synthesis but also catalyze isomerization reactions to enhance iso-alkane content in the product.
3Object-generated harmful factors
If Fischer-Tropsch synthesis is combined with hydrocracking process to improve low-temperature flowability, then iso-alkane content is increased, but investment and operation costs become very high
Solution Approach 1:
The patent combines Fischer-Tropsch synthesis and isomerization functions into a single catalyst system. The cobalt-based active component performs Fischer-Tropsch synthesis to produce linear alkanes, while the modified alumina carrier simultaneously provides isomerization activity to convert linear alkanes to iso-alkanes. This merging of functions into one catalyst eliminates the need for separate hydrocracking units, significantly reducing investment and operation costs while achieving improved low-temperature flowability and high iso-alkane content.
Solution Approach 2:
The modified alumina carrier acts as an intermediary that facilitates isomerization reactions directly on the catalyst support. Instead of requiring a separate hydrocracking process, the carrier's moderate acidity enables in-situ isomerization of the Fischer-Tropsch products, bridging the gap between synthesis and product upgrading within a single reactor system.
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 catalyst achieves high selectivity for kerosene fractions with reduced methane production, increased iso-alkane content, and improved low-temperature flowability, maintaining high reactivity and producing high-quality kerosene with a moderate acidity and three-dimensional pore structure.
Implementation Method 1
A catalyst carrier comprising mesoporous zirconia, silicoaluminophosphate molecular sieve, modified Al-SBA-16, sesbania gum powder, and alumina, with a soluble cobalt salt loaded on the surface, which reduces methane production and enhances isomerization performance
Implementation Method 2
Although a catalyst supported on carbon material as a carrier greatly attenuates the interaction between the active component and the carrier and improves the activity of the catalyst
Implementation Method 3
By selectively breaking chains and isomerizing the linear alkanes produced through Fischer-Tropsch synthesis, the content of iso-alkanes in the product is increased
Data Source
AI summary
A carrier for selectively synthesizing kerosene fraction from syngas, the carrier including the following components in parts by weight: 5-50 parts of mesoporous zirconia (ZrO2), 10-55 parts of a silicoaluminophosphate (SAPO) molecular sieve, 5-50 parts of modified mesoporous molecular sieve Al-SBA-16, 1-3 parts of sesbania gum powder, and 10-70 parts of alumina A catalyst includes a soluble cobalt salt and the aforesaid carrier. The soluble cobalt salt is loaded on the surface of the carrier.