Biobased Propylene Glycol Hydrogenation via Lactide Solubilization
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Solution Overview
Problem
Current processes for producing biobased propylene glycol from renewable resources face challenges such as high costs due to dependence on non-renewable resources and require costly purification of glycerol, as well as high hydrogen pressures and catalyst loadings in the hydrogenation of lactic acid and its esters.
Innovation Solution
A process involving the liquid phase hydrogenation of lactic acid esters in a nonaqueous solvent, specifically propylene glycol, using a copper-containing catalyst like Raney copper, which allows for high solubility of lactide and reduced catalyst fouling, enabling efficient conversion to biobased propylene glycol with mild temperature and pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lactic acid esters are hydrogenated in conventional solvents, then the reaction can proceed, but lactide precipitates out causing reactor plugging and catalyst fouling
Solution Approach 1:
The patent introduces a non-aqueous solvent as an intermediary substance to dissolve lactide and prevent its precipitation. The solvent acts as a mediator between the reactants and the reactor system, ensuring lactide remains in solution throughout the hydrogenation process, thereby preventing reactor plugging and catalyst fouling while maintaining reaction efficiency
Solution Approach 2:
The patent changes the physical-chemical parameters of the reaction system by selecting a specific non-aqueous solvent with appropriate solubility characteristics. This parameter change (switching from conventional solvents to non-aqueous solvents with high lactide solubility) resolves the contradiction by preventing lactide precipitation without compromising reaction productivity
2Productivity
If conventional catalysts are used for lactic acid hydrogenation, then the reaction can proceed, but catalyst fouling and leaching occur reducing efficiency
Solution Approach 1:
The non-aqueous solvent serves as a protective intermediary between the catalyst and the reactants, reducing direct contact and interaction that lead to fouling and leaching. This intermediary role maintains catalyst stability while allowing the hydrogenation reaction to proceed efficiently
Solution Approach 2:
The patent changes the reaction environment parameters by using a non-aqueous solvent system, which alters the catalyst's operating conditions. This parameter change reduces catalyst fouling and leaching, thereby improving both catalyst stability and maintaining conversion rates
3Productivity
If high hydrogen pressure is applied to increase conversion, then reaction rate improves, but operational costs increase
Solution Approach 1:
The patent changes the solvent parameter to a non-aqueous system that enables effective hydrogenation at lower hydrogen pressures. This parameter change reduces the need for high hydrogen pressure while maintaining high conversion rates, thereby lowering operational costs associated with hydrogen consumption and pressure maintenance
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 achieves high selectivity and conversion of lactic acid esters to propylene glycol with reduced corrosion and catalyst leaching, utilizing renewable feedstocks and minimizing operational costs, while maintaining reactor efficiency.
Implementation Method 1
liquid phase hydrogenation of lactic acid esters
Implementation Method 2
in the presence of a catalyst with hydrogen from a hydrogen source
Implementation Method 3
in a nonaqueous solvent in which lactide may be essentially wholly solubilized at the conditions under which the reaction is performed
Data Source
AI summary
A process is described for making a biobased propylene glycol product at least in part from a carbohydrate-derived feed, wherein a feed comprised of a lactic acid ester is reacted with hydrogen in the presence of a catalyst, in a nonaqueous solvent in which lactide may be essentially wholly solubilized at the conditions under which the reaction is carried out, so that lactide does not precipitate out to an extent whereby plugging of the reactor or fouling of the hydrogenation catalyst is observed.