Continuous Lignin Conversion Process for Polyester Production
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Solution Overview
Problem
Current technologies face challenges in implementing a continuous process for converting lignin, particularly due to issues with high-pressure feeding and charging of biomass slurries, and lack an enabling disclosure for maintaining the necessary conditions for effective lignin conversion in a continuous process.
Innovation Solution
A continuous process for converting lignin involves creating a slurry, charging it into a reactor under specific pressure conditions, contacting it with hydrogen in the presence of a catalyst, and removing the products, utilizing a piston pump system with controlled valves to manage pressure and prevent char formation, and ensuring a liquid phase to maintain reactor contents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous process is used for lignin conversion, then productivity is improved, but high-pressure feeding and charging of biomass slurries becomes problematic due to bridging and plugging of orifices and valves
Solution Approach 1:
The patent applies preliminary action by pre-milling the biomass feedstock to a fine particle size (less than 1 mm, preferably less than 500 micrometers) before slurry formation. This preliminary size reduction prevents bridging and plugging in high-pressure feeding systems by ensuring particles are small enough to flow smoothly through orifices and valves, thereby enabling continuous processing without the operational difficulties that would otherwise prevent it.
2Stress or pressure
If slurry pumping systems with ball check valves are used, then high-pressure feeding can be achieved, but fibrous biomass causes bridging and plugging of orifices and valves
Solution Approach 1:
The patent applies parameter changes by modifying the particle size distribution parameter of the biomass feedstock through extensive milling. By reducing particles to less than 1 mm (preferably less than 500 micrometers), the physical parameters of the slurry change such that it no longer exhibits bridging behavior. This parameter modification allows the use of standard ball check valves at high pressures without the reliability issues of plugging that would occur with coarser, fibrous material.
3Manufacturing precision
If batch autoclave processes are used for lignin conversion, then catalytic selectivity to ethylene glycol is high, but the process is not truly continuous and lacks enabling disclosure for continuous operation
Solution Approach 1:
The patent applies continuity of useful action by implementing a fully continuous process where milled biomass is continuously converted to slurry, continuously fed to the reactor, continuously converted to products, and continuously separated. The slurry is formed by mixing milled biomass with water or aqueous solution under conditions that maintain suspension, and this slurry is continuously charged to the reactor. This eliminates batch operations entirely while maintaining the catalytic selectivity for ethylene glycol, achieving both continuous production and high manufacturing precision.
4Productivity
If biomass is ground to small particles for continuous processing, then slurry flow improves, but the fibrous nature may still bridge and plug orifices and valves at small flow rates
Solution Approach 1:
The patent applies local quality by creating a slurry with specific local characteristics - a homogeneous mixture of fine biomass particles (less than 1 mm) suspended in water or aqueous solution. This localized slurry formulation, with controlled particle size distribution and liquid-to-solid ratio, ensures that the material has improved flow properties at the point of feeding. The slurry's homogeneous, particle-level dispersion prevents bridging and plugging even at small flow rates, maintaining operational ease while enabling continuous processing efficiency.
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
The process achieves high yields of usable products, with approximately 80% of available lignin being recovered as oils, and allows for the production of polyester bottles, demonstrating a robust and efficient conversion of lignin in a continuous manner.
Implementation Method 1
charging the slurry comprised of lignin into a lignin conversion reactor having a lignin conversion pressure, wherein the pressure of the slurry comprised of lignin is higher than the lignin conversion pressure
Implementation Method 2
Converting the lignin of the slurry comprised of lignin into lignin conversion products by contacting the lignin with hydrogen in the presence of a first catalyst
Implementation Method 3
contacting the lignin with hydrogen in the presence of a first catalyst
Data Source
AI summary
This specification discloses an operational continuous process to convert lignin as found in ligno-cellulosic biomass before or after converting at least some of the carbohydrates. The continuous process has been demonstrated to create a slurry comprised of lignin, raise the slurry comprised of lignin to ultra-high pressure, deoxygenate the lignin in a lignin conversion reactor over a catalyst which is not a fixed bed without producing char. The conversion products of the carbohydrates or lignin can be further processed into polyester intermediates for use in polyester preforms and bottles.