Guard Bed Reactor for Biofeedstock Olefin Saturation
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Solution Overview
Problem
Acidic biomass feedstocks, such as those used to produce green diesel and pyrolysis oil, are prone to polymerization during hydroprocessing, leading to reactor plugging and pressure drops due to their high acidity, which complicates the production of stable transportation fuels.
Innovation Solution
A guard bed process is employed where the acidic biorenewable feedstock is diluted with deoxygenated feed and treated with a hydroprocessing catalyst at mild conditions to saturate olefins with hydrogen, preventing polymerization, using either noble metal or base metal catalysts supported on various materials, and operating at lower temperatures and higher diluent levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydroprocessing is conducted under normal conditions to saturate olefins, then fuel quality is improved, but polymerization occurs due to high acidity causing reactor plugging and pressure drop
Solution Approach 1:
The patent applies preliminary action by conducting a pre-treatment step before main hydroprocessing. The acidic feedstock is first contacted with a guard bed catalyst at mild conditions to saturate olefins and reduce acidity, preventing polymerization before the feed enters the main hydroprocessing reactor. This preliminary saturation protects the main reactor from plugging while enabling subsequent high-temperature hydroprocessing for fuel production
Solution Approach 2:
The patent uses an intermediary approach by introducing a guard bed catalyst as a protective intermediate layer. This guard bed acts as a mediator between the acidic feedstock and the main hydroprocessing reactor, neutralizing harmful acids and saturating olefins first. The guard bed serves as a buffer that protects the main reactor system from the harmful effects of high acidity while allowing the hydroprocessing to proceed
2Reliability
If high pressure hydrogen is applied to prevent polymerization, then feedstock stability is improved, but processing cost and complexity increase
Solution Approach 1:
The patent applies preliminary action by conducting a pre-treatment step before main hydroprocessing. The acidic feedstock is first contacted with a guard bed catalyst at mild conditions to saturate olefins and reduce acidity, preventing polymerization before the feed enters the main hydroprocessing reactor. This preliminary saturation protects the main reactor from plugging while enabling subsequent high-temperature hydroprocessing for fuel production
Solution Approach 2:
The patent applies parameter changes by operating the guard bed at mild temperatures (50-200°C) and moderate pressures, rather than the high temperature and pressure conditions used in conventional hydroprocessing. This parameter change allows olefin saturation to occur under gentle conditions that prevent polymerization without requiring the extreme conditions that would increase system complexity and cost
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 effectively prevents undesired polymerization, maintaining reactor stability and allowing for the production of upgraded feedstocks for transportation fuels without pressure buildup, as demonstrated by successful tests with different catalyst configurations and recycle ratios.
Implementation Method 1
the olefins are saturated with hydrogen to thereby produce a treated biorenewable feedstock
Implementation Method 2
sent through a guard bed comprising a hydroprocessing catalyst to cause the olefins to be saturated with hydrogen
Data Source
AI summary
The present invention involves a process for processing an acidic biorenewable feedstock comprising olefins, in which the acidic biorenewable feedstock is diluted with a deoxygenated feed to produce a diluted biorenewable feedstock and then is sent through a guard bed comprising a hydroprocessing catalyst to cause the olefins to be saturated with hydrogen and thereby to produce a treated biorenewable feedstock. This treated biorenewable feedstock can then be treated under standard hydroprocessing condition to produce an upgraded feedstock for transportation fuels.