UZM-44 Zeolite Dehydrocyclodimerization Catalyst
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Solution Overview
Problem
Current zeolites, such as IM-5, have limited diffusion due to interrupted connectivity in the third dimension and varying channel sizes, which restricts their effectiveness in dehydrocyclodimerization reactions, particularly in producing high yields of aromatics and hydrogen from aliphatic hydrocarbons.
Innovation Solution
Development of a new aluminosilicate zeolite, UZM-44, with a three-dimensional framework and specific empirical composition, which is thermally stable up to 800°C and optimized for dehydrocyclodimerization reactions using a process involving reactive sources of sodium, organic structure directing agents, and optional elements like gallium, iron, or boron, to enhance catalytic activity and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If IM-5 zeolite is used for dehydrocyclodimerization, then catalytic activity is achieved, but diffusion is limited due to interrupted connectivity in the third dimension and varying channel sizes
Solution Approach 1:
The patent transitions from the IM-5 zeolite structure with interrupted three-dimensional connectivity to the UZM-44 structure with continuous three-dimensional channel connectivity. This dimensional improvement allows uninterrupted diffusion pathways throughout the crystal structure, resolving the diffusion limitation while preserving catalytic activity in the third dimension.
2Device complexity
If IM-5 zeolite with multiple different sizes of 10-membered ring channels is used, then structure complexity is achieved, but channel size uniformity is poor
Solution Approach 1:
The UZM-44 zeolite structure provides uniform channel dimensions throughout the crystal lattice, ensuring consistent pore size and shape. This uniformity in local channel properties enables precise control over reactant and product diffusion, improving manufacturing precision compared to the varying channel sizes in IM-5.
3Productivity
If conventional zeolites are used for dehydrocyclodimerization, then aromatic production is achieved, but thermal stability up to 800°C is insufficient
Solution Approach 1:
The UZM-44 zeolite employs a composite aluminosilicate framework with specific elemental composition (Si, Al, and other elements) that provides enhanced thermal stability. This composite structure maintains structural integrity and catalytic activity at temperatures up to 800°C, overcoming the thermal stability limitations of conventional zeolites while preserving high aromatic production capability.
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
UZM-44 achieves a high yield of aromatics and hydrogen with a light ends byproduct and C2-C4 recycle product, demonstrating improved thermal stability and catalytic performance compared to existing zeolites, thus overcoming the limitations of IM-5 and other zeolites in dehydrocyclodimerization reactions.
Implementation Method 1
UZM-44 may be used as a catalyst in dehydrocyclodimerization reactions where aliphatic hydrocarbons containing from 2 to 6 carbon atoms per molecule are reacted over a catalyst to produce a high yield of aromatics and hydrogen
Implementation Method 2
Zeolites are characterized by having pore openings of uniform dimensions... Zeolites can be used as catalysts for hydrocarbon conversion reactions, which can take place on outside surfaces as well as on internal surfaces within the pore
Implementation Method 3
Synthetic zeolites are prepared via hydrothermal synthesis employing suitable sources of Si, Al and structure directing agents such as alkali metals, alkaline earth metals, amines, or organoammonium cations. The structure directing agents reside in the pores of the zeolite and are largely responsible for the particular structure that is ultimately formed
Data Source
AI summary
A process for dehydrocyclodimerization using a catalytic composite comprising at least one of a new family of aluminosilicate zeolites designated UZM-44 has been developed. These zeolites are represented by the empirical formula.NanMmk+TtAl1-xExSiyOz where “n” is the mole ratio of Na to (Al+E), M represents a metal or metals from zine, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, “m” is the mole ratio of M to (Al+E), “k” is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. UZM-44 has catalytic properties for carrying processes involving contacting at least one aliphatic hydrocarbon having from 2 to about 6 carbon atoms per molecule with the UZM-44 to produce at least one aromatic hydrocarbon.