Bifunctional Catalyst for Renewable Feedstock Hydroconversion
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Solution Overview
Problem
The challenge lies in the inability of existing processes to effectively incorporate hydrotreated paraffins from renewable sources into kerosene or gas oil due to their high pour points and boiling points, which leads to setting issues at low temperatures, necessitating additional hydroconversion steps like hydroisomerization and hydrocracking to improve cold properties and compatibility.
Innovation Solution
A process utilizing a bifunctional catalyst with a molybdenum and/or tungsten sulfide phase promoted with nickel and/or cobalt, operating under conditions where the partial pressure of hydrogen sulfide is reduced below conventional levels, enhances the activity and selectivity of the hydroconversion catalyst, improving cold properties and yield of middle distillate cuts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrotreating is performed to produce paraffins from renewable feedstocks, then the liquid effluent is substantially free of sulfur, nitrogen and oxygen impurities, but the pour point is high and cold properties are insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the hydroconversion conditions (temperature, pressure, catalyst composition) to transform linear paraffins into branched paraffins with improved cold properties. The catalyst contains specific metal phases (Ni, Co, Mo, W) with controlled ratios and sulfur content to achieve optimal hydroisomerization activity while maintaining hydro treating function.
Solution Approach 2:
The patent uses composite catalyst materials combining multiple metal phases (nickel, cobalt, molybdenum, tungsten) with silica-alumina support. This composite structure provides both hydro treating activity and hydroisomerization capability, allowing simultaneous improvement of purity and cold properties through integrated catalysis.
2Temperature
If hydroisomerization is performed to improve cold properties, then branched paraffins are formed with better low-temperature flow properties, but additional processing steps and catalyst complexity are required
Solution Approach 1:
The patent implements multi-functionality by designing a single catalyst that performs both hydro treating and hydroisomerization reactions. The catalyst contains metal phases (Ni, Co, Mo, W) that provide hydrogenation activity while the silica-alumina support provides acid sites for isomerization, eliminating the need for separate processing units.
Solution Approach 2:
The patent merges two separate catalytic functions (hydro treating and hydroisomerization) into one integrated catalyst system. This combination allows the liquid effluent to be simultaneously purified and converted to improved cold properties in a single processing step, reducing overall process complexity.
3Temperature
If hydrocracking is performed to adjust distillation curve for kerosene pool, then molecular weight is reduced and boiling point is lowered, but light cracking products may be produced that are too light for incorporation
Solution Approach 1:
The patent applies parameter changes by controlling hydroconversion conditions (temperature, pressure, LHSV) and catalyst composition to optimize the balance between hydrocracking and hydroisomerization. By adjusting these parameters, the process selectively produces C9-C16 branched paraffins suitable for kerosene while minimizing excessive cracking to light gases.
Solution Approach 2:
The patent employs feedback control through careful selection of catalyst metal ratios (Ni:Mo or Co:W between 1:4 and 1:1) and sulfur content (0.1-5 wt%) to regulate reaction selectivity. This feedback mechanism ensures optimal distribution of products within the kerosene boiling range while maintaining high overall yield.
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 reduces the temperature required for target cold property values, increases the yield of middle distillate cuts, and enhances the resistance of the catalyst to deactivation and oxygenated compounds, while maintaining the sulfurized form of the catalyst.
Implementation Method 1
The hydroconversion step is performed on a bifunctional catalyst containing both a hydro/dehydrogenating function and a Brønsted acid function
Implementation Method 2
hydro-deoxygenation leading to the formation of water by consumption of hydrogen and to the formation of hydrocarbons with a carbon number (Cn) equal to that of the initial fatty acid chains
Data Source
AI summary
The present invention describes a process for treating a feedstock obtained from a renewable source, comprising a step a) of hydrotreating said feedstock, a step b) of separation into at least a light fraction and at least a hydrocarbon liquid effluent, a step c) of removing at least a portion of the water from the hydrocarbon liquid effluent, a step d) of hydroconversion of at least a portion of the hydrocarbon liquid effluent, said hydroconversion step d) being characterized firstly by the use of a bifunctional catalyst comprising a molybdenum and/or tungsten sulfide phase promoted with nickel and/or cobalt and secondly by a ratio between the partial pressure of hydrogen sulfide and of hydrogen at the inlet of the hydroconversion unit of 10 less than 5×10−5 and a step e) of fractionation of the effluent obtained from step d) to obtain at least a middle distillate fraction.