Ni-Mo Catalyst Hydrodeoxygenation Selectivity
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Solution Overview
Problem
Existing processes for hydrogenation of triglycerides in vegetable oils face challenges such as high hydrogen consumption, catalyst deactivation, corrosion due to CO and CO2 formation, and loss of valuable paraffinic products, particularly due to decarboxylation/decarbonylation reactions during hydrotreatment.
Innovation Solution
A process using a catalyst with a specific atomic ratio of metal from group VIII to metal from group VIB, such as Ni/Mo, in a fixed bed reactor system, which controls the selectivity towards hydrodeoxygenation reactions, minimizing decarboxylation/decarbonylation and reducing hydrogen consumption, and employing a low recycle ratio to maintain efficient temperature control and product yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If decarboxylation/decarbonylation reactions are promoted to reduce hydrogen consumption, then hydrogen consumption decreases, but valuable paraffin product is lost and catalyst deactivation occurs due to CO inhibition
Solution Approach 1:
The patent applies parameter changes by precisely controlling the atomic ratio of group VIII to group VIB metals in the catalyst (specifically Ni/Mo ratio between 0.02-0.05), and by controlling reaction conditions (temperature 200-400°C, pressure 5-50 bar) to favor hydrodeoxygenation over decarboxylation/decarbonylation pathways, thereby reducing hydrogen consumption while preserving paraffin products
Solution Approach 2:
The patent uses composite catalyst materials combining metals from group VIII (Ni, Co) and group VIB (Mo, W) in specific ratios, supported on alumina or silica-alumina. This composite structure creates synergistic effects that enhance hydrodeoxygenation activity while suppressing unwanted decarboxylation/decarbonylation reactions that lead to paraffin loss
2Use of energy by moving object
If decarboxylation/decarbonylation reactions occur during hydrotreatment, then hydrogen consumption is reduced, but catalyst deactivation occurs due to CO inhibition
Solution Approach 1:
The patent controls reaction parameters (temperature 200-400°C, pressure 5-50 bar, H2/feed ratio 100-1000 Nm³/m³) and catalyst composition (Ni/Mo atomic ratio 0.02-0.05) to suppress decarboxylation/decarbonylation reactions that produce CO, thereby preventing catalyst deactivation while still achieving efficient hydrodeoxygenation with moderate hydrogen consumption
Solution Approach 2:
The composite catalyst system with specific metal ratios and support materials creates a selective catalytic environment that promotes hydrodeoxygenation while minimizing CO-producing side reactions, thus maintaining catalyst activity and reliability over time
3Temperature
If high recycle ratio is used to provide sufficient diluting agent, then temperature control is improved, but hydraulic downstream load increases and reactor volume must be enlarged
Solution Approach 1:
The patent optimizes the recycle ratio parameter to a specific range (5-30:1 dilution agent to fresh feed) that provides sufficient temperature control while avoiding excessive hydraulic load. The process uses this controlled recycling to maintain reaction temperature within 200-400°C without requiring oversized reactor volumes
Solution Approach 2:
The patent applies partial recycling rather than full recycling, using just enough recycle stream (5-30:1 dilution ratio) to control the exothermic reactions and maintain temperature control, avoiding the excessive hydraulic load and reactor enlargement that would result from higher recycle ratios
4Use of energy by moving object
If decarboxylation/decarbonylation reactions occur, then hydrogen consumption is reduced, but corrosiveness increases due to CO2 presence
Solution Approach 1:
The patent controls reaction conditions (temperature 200-400°C, pressure 5-50 bar) and catalyst composition to suppress decarboxylation/decarbonylation reactions that produce CO2, thereby minimizing corrosiveness while achieving efficient hydrodeoxygenation with moderate hydrogen consumption
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 maximizes the yield of base gas oil and kerosene, limits the formation of carbon oxides, and maintains catalyst activity, achieving high conversion rates with minimal side reactions and corrosion, thus optimizing hydrodeoxygenation selectivity and reducing operational costs.
Implementation Method 1
a hydrogenation catalyst which comprises an active phase constituted by at least one element from group VIB and at least one element from group VIII, said elements being in the sulphide form
Implementation Method 2
continuous hydrogenation of triglyceride containing raw materials
Implementation Method 3
the catalytic hydrotreating of animal and vegetable oils and fats to produce saturated hydrocarbons which e.g. may be useful as diesel and/or kerosene fuels. Such hydrotreating comprises the removal of unsaturations and the hydrodeoxygenation of the triglycerides
Implementation Method 4
Due to the highly exothermic nature of these reactions, temperature control is very important to avoid undesirable side reactions
Data Source
Figure 1
AI summary
Process for the continuous hydrogenation of triglyceride containing raw materials in a fixed bed reactor system having several catalyst beds arranged in series and comprising at least e hydrogenation catalyst comprising an active phase constituted by a nickel and molybdenum element. The raw material feed, hydrogen containing gas and diluting agent are passed together through the catalyst beds at hydrogenation conditions. The raw material feed stream as well as the stream of hydrogen containing gas are divided into an equal number of different partial streams. These are each passed to one catalyst bed in such a manner that the weight ratio of diluting agent to raw material feed is essentially the same at the entrance of all catalyst beds and does not exceed 4:1. The claimed process is preferably conducted at low temperatures and allows the utilization of existing units due to the low recycle ratio.