Alkanol Dehydrogenation for Aromatic Yield
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Solution Overview
Problem
The existing methods for converting alkanols to hydrocarbons result in a low yield of aromatic hydrocarbons, such as benzene, toluene, and xylenes, limiting their application in producing high-value aromatic chemicals.
Innovation Solution
A two-step process involving dehydrogenation and oxygenate conversion, where alkanols are exposed to a dehydrogenation catalyst to produce an oxygenate component with a specific hydrogen-to-carbon effective ratio, followed by exposure to an oxygenate conversion catalyst at controlled temperatures and pressures to enhance aromatic hydrocarbon production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If alkanols are converted to hydrocarbons using traditional oxygenate conversion catalysts, then the process is simple and direct, but the aromatic yield is low and the aromatic-to-paraffin ratio is poor
Solution Approach 1:
The conversion process is divided into two distinct steps: first, dehydrogenation of alkanols to aldehydes/ketones using a dehydrogenation catalyst; second, conversion of the oxygenate component to hydrocarbons using an oxygenate conversion catalyst. This segmentation allows optimization of each step for maximum aromatic production, resolving the contradiction between high aromatic yield and process simplicity.
Solution Approach 2:
The dehydrogenation step is performed as a preliminary action before the oxygenate conversion. By pre-converting alkanols to aldehydes or ketones and removing excess hydrogen, the feedstock is prepared in an optimal state for the subsequent conversion step, thereby maximizing aromatic yield while maintaining a manageable process structure.
2Productivity
If the hydrogen-to-carbon effective ratio of the feed is high (as in alkanols), then the feed is easy to process, but the product distribution favors paraffins over aromatics
Solution Approach 1:
The dehydrogenation step changes the hydrogen-to-carbon effective ratio of the feedstock by removing hydrogen in the form of H2 gas. This parameter change transforms the high H:C eff ratio alkanol feed into an oxygenate component with a lower, more favorable H:C eff ratio for aromatic production, thereby shifting the product distribution toward aromatics while maintaining ease of processing.
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 process significantly increases the yield of aromatic hydrocarbons, with over 40% of the carbon from the alkanol feedstock being contained within the aromatic hydrocarbon product, improving the aromatic-to-paraffin ratio and overcoming the limitations of traditional methods.
Implementation Method 1
exposing an alkanol feedstock to a dehydrogenation catalyst at a dehydrogenation temperature and a dehydrogenation pressure to produce hydrogen and an oxygenate component
Implementation Method 2
exposing the oxygenate component to an oxygenate conversion catalyst at an oxygenate conversion temperature of between 250°C and 550°C and an oxygenate conversion pressure of from less than atmospheric pressure to 7 x 106 pa
Data Source
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AI summary
The present invention provides methods, reactor systems, and catalysts for increasing the yield of aromatic hydrocarbons produced while converting alkanols to hydrocarbons. The invention includes methods of using catalysts to increase the yield of benzene, toluene, and mixed xylenes in the hydrocarbon product.