Hydrotreating Catalyst Silicon Removal Tartaric Acid Impregnation
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Solution Overview
Problem
Silicon species adsorb on catalyst surfaces, forming strong bonds with alumina hydroxyl sites, reducing active sites and leading to catalyst deactivation in hydroprocessing units.
Innovation Solution
A hydroprocessing catalyst prepared by impregnating a composition of Group VIB, Group VIIIB, and Group Va oxides with an organic acid, particularly tartaric acid, effectively removes silicon from hydrocarbon feeds by maintaining available hydroxyl sites on the alumina surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If silicon species adsorb on catalyst surface forming strong bonds with alumina hydroxyl sites, then silicon removal from feed is achieved, but active sites are reduced leading to catalyst deactivation
Solution Approach 1:
The patent applies preliminary action by pre-impregnating the alumina support with organic acid (particularly tartaric acid) before adding metal oxides. This creates a protective layer that modifies the alumina surface properties in advance, enabling the catalyst to selectively adsorb silicon species while preserving hydroxyl sites for subsequent hydrotreating reactions. The organic acid treatment is performed before catalyst activation, establishing the desired surface chemistry beforehand.
Solution Approach 2:
The organic acid (tartaric acid) serves as an intermediary substance that mediates between the alumina support and silicon species. It modifies the alumina surface to create selective adsorption sites for silicon while maintaining catalytic activity. The organic acid decomposes during activation to leave behind a modified surface structure that preferentially binds silicon species, acting as a bridge between silicon removal function and catalyst activity preservation.
2Object-affected harmful factors
If organic acid with at least two carboxylic groups is used during impregnation, then silicon pickup is enhanced, but carbon residue may form on catalyst
Solution Approach 1:
The patent applies parameter changes by carefully controlling the impregnation conditions including organic acid concentration, impregnation temperature, and subsequent drying/activation parameters. These parameter optimizations ensure that the organic acid (particularly tartaric acid) decomposes completely during activation to form the desired surface modification without leaving excessive carbon residue. The multi-carboxylic group structure of tartaric acid provides better controlled decomposition behavior compared to simpler organic acids.
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 catalyst achieves enhanced silicon removal and maintains hydrotreating activity, with higher silicon pickup and similar hydrotreating performance compared to baseline, while minimizing carbon residue on the catalyst.
Implementation Method 1
impregnating a composition comprising about 1-20 wt % Group VIB metal oxide, 1-10 wt % Group VIIIB metal oxide, and 1-10 wt % a Group Va oxide with an impregnating solution containing at least one organic acid
Implementation Method 2
Silicon species adsorb on the catalyst surface by forming a strong bond with the alumina (hydroxyl sites) on the catalyst
Data Source
AI summary
A hydroprocessing catalyst is provided that is made with an organic acid, such as tartaric acid, that provides for an improved capacity for removal of silicon from hydrocarbon feeds. The silicon acts as a poison to the catalyst when not removed. The catalyst has more available hydroxyl sites than catalysts made using other impregnation liquids besides tartaric acid.