Hybrid Catalyst Acidity Tuning for Propane-Selective Paraffin Synthesis
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Solution Overview
Problem
Existing synthetic processes for converting carbon-containing streams to C2 to C5 paraffins, such as propane, suffer from low carbon conversion and selectivity, often favoring methane or ethane production over propane, and require high operating temperatures.
Innovation Solution
A hybrid catalyst comprising a metal oxide component and a microporous catalyst component, specifically SSZ-13 zeolite, is used to convert hydrogen and carbon-containing gases into C2 to C5 paraffins at lower temperatures (≤380°C) with high selectivity to propane, utilizing a Brönsted acid site concentration ≥0.25 mmol/g and strength from 380°C to 500°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts are used for converting carbon-containing streams to C2 to C5 paraffins, then the process can operate, but carbon conversion is low and selectivity favors methane or ethane over propane
Solution Approach 1:
The patent employs a hybrid catalyst system combining two distinct catalyst components: a metal oxide component (containing Cu, Zn, Al, and optionally Ga, In, or La) and a microporous catalyst component (such as SAPO-34, SSZ-13, or CHA zeolite). This composite catalyst structure enables synergistic effects where the metal oxide component facilitates high carbon conversion while the microporous component provides shape selectivity and acid catalysis to favor C3/C4 paraffin production, thereby resolving the contradiction between conversion and selectivity.
Solution Approach 2:
The microporous catalyst component introduces localized acidic sites with specific pore structures that create favorable local environments for C3/C4 paraffin formation. The confined pore spaces and acid sites within the microporous material provide localized catalytic functionality that directs product selectivity toward propane and butane, while the metal oxide component maintains overall high conversion activity.
2Productivity
If high carbon conversion to C2 to C5 paraffins is achieved, then productivity improves, but operating temperature must be increased
Solution Approach 1:
The hybrid catalyst combines metal oxide and microporous catalyst components that work synergistically to achieve high carbon conversion at reduced temperatures. The metal oxide component maintains high catalytic activity at lower temperatures, while the microporous component provides shape selectivity, enabling the system to achieve >99.9% carbon conversion at temperatures of 200-400°C, significantly lower than conventional processes.
3Productivity
If conventional catalysts are used, then the process is simpler, but much of the feed carbon either does not get converted or is converted to less desirable hydrocarbons
Solution Approach 1:
The hybrid catalyst system ensures near-complete conversion of feed carbon (>99.9%) by combining the high conversion capability of metal oxide catalysts with the selective catalysis of microporous materials. This prevents carbon from exiting unconverted or forming undesired byproducts, as the synergistic catalyst system efficiently directs all carbon toward C2-C5 paraffin formation.
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 hybrid catalyst achieves high carbon conversion (>99.9%) and a C3/C2 molar ratio ≥4.0, producing a high yield of C2 to C5 paraffins, particularly propane, with improved selectivity and efficiency compared to conventional catalysts.
Implementation Method 1
wherein a Brönsted acid site concentration of the microporous catalyst component is greater than or equal to 0.25 mmol/g, and a Brönsted acid site strength measured as ammonia desorption peak temperature from 380 °C to 500 °C
Implementation Method 2
a metal oxide catalyst component comprising a metal component present on a metal oxide support material
Data Source
Figure 1
AI summary
A method for preparing C2 to C5 paraffins including introducing a feed stream of hydrogen gas and a carbon-containing gas selected from carbon monoxide, carbon dioxide, and mixtures thereof into a reaction zone of a reactor. Converting the feed stream into a product stream that includes C2 to C5 paraffins in the reaction zone in the presence of a hybrid catalyst. The hybrid catalyst including a microporous catalyst component; and a metal oxide catalyst component. The metal oxide catalyst component including a metal component present on a metal oxide support material. The metal oxide support material includes at least one oxide of a metal selected from Group 4 of the IUPAC periodic table of elements. The product stream has a C3/C2 carbon molar ratio greater than or equal to 4.0.