Hydroisomerization Catalyst for Fischer-Tropsch Middle Distillates

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Solution Overview

Problem

The Fischer-Tropsch process produces hydrocarbons with poor cold-resistance properties, making them unsuitable for use as middle distillates like diesel oil and kerosene due to high pour points, and existing hydroisomerization catalysts have limitations in achieving optimal conversions and selectivity.

Innovation Solution

A process utilizing a specific silica-alumina catalyst with a noble metal component, optimized pore structure, and specific physico-chemical characteristics for hydrocracking and hydroisomerization to improve the cold properties and yield of middle distillates from Fischer-Tropsch-derived paraffins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Fischer-Tropsch process produces linear hydrocarbons, then hydrocarbons are free of heteroatomic impurities, but cold-resistance properties are poor with high pour points

Engineering Contradiction:

Improvepurity of hydrocarbonsVSAvoidpour point

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent applies parameter changes by modifying the molecular structure of linear hydrocarbons through hydroisomerization reactions. The catalyst system (bifunctional catalyst with metal function and acid function) facilitates isomerization that changes the molecular configuration from linear to branched structures, thereby lowering the pour point from +37°C to below -15°C while maintaining the purity free of heteroatomic impurities.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If conventional hydroisomerization catalysts are used, then some conversion is achieved, but optimal conversion rates and selectivity are not reached

Engineering Contradiction:

Improveconversion rateVSAvoidselectivity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent employs a composite catalyst system combining metal functions (Group VIII metals like Pt, Pd, Rh, Ir, Ru) with acid functions (alumina, silica-alumina, or zeolites). This composite structure enables simultaneous hydroisomerization and hydrocracking activities, achieving high conversion rates (90-95%) while maintaining excellent selectivity for middle distillate products (C5-C20 hydrocarbons) with desired cold properties.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The catalyst design applies local quality by creating specific active sites with different functions within the same catalyst system. The metal sites provide hydrogenation/dehydrogenation activity while the acid sites provide isomerization activity, allowing localized chemical transformations that optimize both conversion and selectivity for specific product ranges.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If heavy fraction (370°C+) is converted to middle distillates, then yield increases, but catalyst deactivation and selectivity control become challenges

Engineering Contradiction:

Improveyield of middle distillatesVSAvoidcatalyst activity

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The patent implements continuous operation with catalyst regeneration capabilities. The hydrocracking unit is designed to maintain continuous conversion of heavy fractions (370°C+) to middle distillates while incorporating means for catalyst regeneration, ensuring sustained catalyst activity and preventing deactivation over extended operation periods.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The process incorporates feedback control through monitoring of conversion rates, product distribution, and catalyst performance. This enables adjustment of operating conditions (temperature, pressure, space velocity) to maintain optimal selectivity and conversion while detecting early signs of catalyst deactivation for timely regeneration or replacement.

Inventive Principle:

Principle #23Feedback

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

Significantly enhances the cold properties of the resulting middle distillates, increasing their yield and achieving high conversion rates of heavy paraffins to diesel and kerosene fractions, while maintaining catalyst activity and selectivity.

Implementation Method 1

The unit is designed to facilitate hydrocracking reactions

Methodology Applied

Scientific EffectHydrocracking:

Implementation Method 2

facilitate hydroisomerization reactions, thereby making it possible to obtain highly selective and active catalysts

Methodology Applied

Scientific EffectHydroisomerization:

Data Source

PatentUS7704378B2Method for the production of middle distillates by hydroisomerisation et hydrocracking of charges arising from the Fischer-Tropsch method

Publication Date: 2010.04.27 IFP ENERGIES NOUVELLES

AI summary

The invention relates to a process for preparing middle distillates from a paraffinic feedstock produced by Fischer-Tropsch synthesis, using a hydrocracking/hydroisomerization catalyst which comprises at least one hydrodehydrogenating element chosen from the group formed by the noble elements of Group VIII of the periodic table, a silica-alumina-based non-zeolitic support obtained from wherein the non-zeolitic silica-alumina based support was obtained from a process comprising starting from a mixture of a partially soluble alumina compound in an acid medium with a totally soluble silica compound or with a totally soluble combination of alumina and hydrated silica, the resultant moldable mixture is concentrated to form a moldable mixture, the resultant mixture is molded and the resultant molded article is subjected to a hydrothermal or thermal treatment.