Selective Hydrogenation via Flow Index Control
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Solution Overview
Problem
The challenge in the selective hydrogenation of unsaturated hydrocarbons is the potential for runaway reactions and the difficulty in converting highly unsaturated hydrocarbons to unsaturated hydrocarbons efficiently, particularly due to the limitations of existing hydrogenation catalysts.
Innovation Solution
A process involving a hydrogenation catalyst with a selectivity of 90 mol% or greater for converting highly unsaturated hydrocarbons to unsaturated hydrocarbons, operated under specific conditions defined by a flow index (IF) ranging from 0.09 to 35, which includes a hydrogenation step in a reaction zone with a catalyst that effectively minimizes runaway reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a highly selective hydrogenation catalyst is used to minimize runaway reactions, then selectivity for converting highly unsaturated hydrocarbons to unsaturated hydrocarbons is improved (90 mol% or greater), but the difficulty in efficiently converting highly unsaturated hydrocarbons increases due to catalyst limitations
Solution Approach 1:
The patent introduces a flow index (IF) parameter that combines flow rate, carbon monoxide concentration, and reaction zone volume to optimize reaction conditions. By controlling the IF within specific ranges (0.09-35, preferably 0.27-25, more preferably 0.4-20, most preferably 1.0-5.6), the process achieves both high selectivity (90 mol% or greater) and efficient conversion of highly unsaturated hydrocarbons, resolving the contradiction between selectivity and conversion efficiency
Solution Approach 2:
Carbon monoxide is introduced as an intermediary substance in the hydrocarbon stream. The presence of CO at controlled concentrations (0.0001-0.15 mol%, preferably 0.001-0.15 mol%, more preferably 0.01-0.15 mol%) acts as a moderator that enhances catalyst selectivity while maintaining conversion efficiency, effectively mediating between the competing requirements of high selectivity and efficient conversion
2Productivity
If hydrogenation conditions are intensified to improve conversion rate, then productivity increases, but the risk of runaway reactions increases
Solution Approach 1:
The flow index serves as a feedback-controlled parameter that continuously balances conversion rate and safety. By monitoring and adjusting the combination of flow rate, CO concentration, and reaction zone volume to maintain IF within optimal ranges, the process achieves high productivity while preventing runaway reactions through dynamic condition optimization
Solution Approach 2:
Carbon monoxide is introduced beforehand as a safety cushion in the hydrocarbon stream. The pre-present CO molecules provide a protective effect that suppresses excessive hydrogenation activity, allowing high conversion rates to be achieved while maintaining reliability and preventing runaway reactions
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 approach achieves high conversion rates of highly unsaturated hydrocarbons to unsaturated hydrocarbons while maintaining catalyst selectivity and stability, reducing the risk of runaway reactions and allowing for efficient operation across varying carbon monoxide concentrations.
Implementation Method 1
hydrogenating, in a reaction zone, a highly unsaturated hydrocarbon received from a hydrocarbon stream to yield a product comprising an unsaturated hydrocarbon
Implementation Method 2
the hydrogenating step occurs in the presence of a hydrogenation catalyst which has a selectivity for conversion of the highly unsaturated hydrocarbon to the unsaturated hydrocarbon of about 90 mol % or greater
Data Source
AI summary
A process includes hydrogenating, in a reaction zone, a highly unsaturated hydrocarbon received from a hydrocarbon stream to yield a product having an unsaturated hydrocarbon, the hydrogenating step occurring in the presence of a hydrogenation catalyst which has a selectivity for conversion of the highly unsaturated hydrocarbon to the unsaturated hydrocarbon of about 90 mol % or greater based on the moles of the highly unsaturated hydrocarbon which are converted to the product, the hydrogenating step occurring in a reaction zone under conditions which include a flow index (IF) in a range of about 0.09 to about 35, wherein the IF is defined as:IF=F×[CO]V,wherein F is the flow rate of the hydrocarbon stream into the reaction zone in units of kg/h, [CO] is the concentration of carbon monoxide in the hydrocarbon stream in units of mol %, and V is the volume of the reaction zone in units of ft3.