Oxygen-Free Oxidative Dehydrogenation Catalyst
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Solution Overview
Problem
Conventional oxidative dehydrogenation processes for converting alkanes to olefins require a feed stream of oxygen, increasing costs and risks due to combustion hazards, and necessitate fixed bed reactors with downtime for catalyst regeneration.
Innovation Solution
Development of an oxidative dehydrogenation catalyst with a crystalline structure of oxides of molybdenum, vanadium, and niobium, promoted by bismuth, antimony, or praseodymium, which allows for stable redox cycling and eliminates the need for gaseous oxygen, enabling conversion in a circulating reactor and regeneration using air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional oxidative dehydrogenation catalysts with oxygen co-feed are used, then dehydrogenation of alkanes to olefins can be achieved, but combustion hazards increase and operational costs increase
Solution Approach 1:
The patent removes oxygen from the feed stream entirely, extracting the harmful element (oxygen) from the system. The catalyst is designed to perform dehydrogenation without requiring oxygen co-feed, thereby eliminating combustion hazards while maintaining the dehydrogenation function.
Solution Approach 2:
The patent changes the operational parameters by eliminating oxygen from the feed composition and adjusting the catalyst formulation to include specific promoters (Bi, Sb, Pr) that enable dehydrogenation under oxygen-free conditions. This parameter change resolves the contradiction by making the process inherently safer while maintaining functionality.
2Productivity
If conventional fixed bed reactors are used with oxidative dehydrogenation catalysts, then dehydrogenation can be performed, but downtime for catalyst regeneration increases
Solution Approach 1:
The patent transitions from static fixed bed operation to dynamic circulating reactor operation. The catalyst continuously circulates between the reactor and regenerator, allowing simultaneous reaction and regeneration operations. This dynamic approach eliminates downtime by maintaining continuous catalyst movement and function.
Solution Approach 2:
The circulating reactor design ensures continuous useful action by maintaining constant catalyst circulation. While catalyst is being regenerated in one location, fresh regenerated catalyst continuously replaces spent catalyst in the reaction zone, ensuring uninterrupted dehydrogenation operation and eliminating idle regeneration downtime.
3Reliability
If oxygen co-feed is used in dehydrogenation processes, then oxidative dehydrogenation can proceed, but operational costs increase
Solution Approach 1:
The catalyst system becomes self-sufficient by using its own lattice oxygen for the dehydrogenation reaction, eliminating the need for external oxygen co-feed. The catalyst regenerates its oxygen supply during circulation in the regenerator, making the system self-service and eliminating oxygen consumption costs.
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 solution achieves adequate conversion and selectivity of ethane to ethylene without oxygen co-feed, reducing operational costs and eliminating combustion risks, while maintaining catalyst stability and activity over time.
Implementation Method 1
allows for stable redox cycling and eliminates the need for gaseous oxygen
Implementation Method 2
contacting a feed stream comprising alkanes with an oxidative dehydrogenation catalyst in a reaction zone, where the oxidative dehydrogenation catalyst does not comprise tellurium; and dehydrogenating the alkanes in the reaction zone
Data Source
AI summary
A method for converting alkanes to olefins includes contacting a feed stream comprising alkanes with an oxidative dehydrogenation that does not comprise tellurium catalyst in a reaction zone and dehydrogenating the alkanes without a co-feed of oxygen to yield a product stream having olefins. The oxidative dehydrogenation catalyst has the formula: MovVwNbyAzOx, where v is 1.0, w is from 0.1 to 0.5, y is from 0.001 to 0.3, A is Bi, Sb, Pr, or mixtures thereof, z is from 0.01 to 0.3, and x charge-balances the structure. The oxidative dehydrogenation catalyst has a crystallographic structure with Pba2-32 space group, characterized by reflections determined with Cu-Kα X-ray diffraction (XRD) as follows.