Hydrotreating Catalyst Rejuvenation via Citric Acid Impregnation
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Solution Overview
Problem
Current hydrotreating catalyst rejuvenation processes are inefficient, particularly when using citric acid alone, as they fail to restore catalytic activity to levels comparable to fresh catalysts, and often require additional organic additives for satisfactory results.
Innovation Solution
A process involving regeneration of hydrotreating catalysts with an oxygen-containing gas, followed by impregnation with a citric acid and water solution, aging, and drying, which enhances catalytic activity without the need for additional organic additives, forming stable complexes and improving dispersion of metal oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If citric acid alone is used for catalyst rejuvenation, then the process simplicity is improved, but the catalytic activity restoration is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the impregnation solution by specifying precise citric acid concentrations (5-20 wt%) and molecular ratios (0.1-0.3 mol citric acid per mol of metal), along with controlled aging temperatures (25-100°C) and times (1-7 days). These parameter optimizations enable citric acid alone to achieve superior catalyst rejuvenation without additional organic additives, resolving the contradiction between process simplicity and activity restoration.
2Reliability
If additional organic additives are used with citric acid, then the catalytic activity restoration is improved, but the process complexity increases
Solution Approach 1:
The patent extracts and eliminates the need for additional organic additives from the rejuvenation process. By optimizing the citric acid concentration and aging conditions, the invention achieves effective catalyst rejuvenation using citric acid alone, removing the complexity of managing multiple additives while maintaining or improving catalytic activity restoration.
Solution Approach 2:
The patent enables citric acid to perform the complete rejuvenation function independently without requiring supplementary organic additives. The citric acid solution, when applied at optimized concentrations and aged under controlled conditions, self-sufficiently restores catalytic activity by forming stable surface complexes and improving metal dispersion, thereby eliminating the need for additional chemical agents.
3Loss of substance
If conventional regeneration is performed, then the carbon content is reduced, but the catalytic activity does not恢复到 fresh catalyst levels
Solution Approach 1:
The patent applies preliminary citric acid impregnation and aging treatment to the regenerated catalyst before its final use. This preliminary action of forming citrate complexes during the aging stage (25-100°C for 1-7 days) prepares the catalyst surface in advance, enabling subsequent high catalytic activity that exceeds even fresh catalyst performance, thereby addressing the insufficient activity restoration after conventional regeneration.
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 process significantly improves catalytic activity, with relative volume activity (RVA) measurements exceeding those of fresh catalysts, demonstrating rejuvenated catalysts with activities up to twice that of previously reported methods, and in some cases, surpassing the activity of fresh catalysts.
Implementation Method 1
regenerating the catalyst by contacting said catalyst with an oxygen containing gas at a temperature from about 300° C. to 550° C. to obtain a regenerated carbon-reduced catalyst wherein the content of carbon at the end of the regeneration step a) is inferior to 0.5 wt %
Implementation Method 2
impregnating the regenerated, carbon-reduced catalyst with a solution which consists of a mixture of water and citric acid
Implementation Method 3
The impregnation solution consists of a combination of water and a rejuvenating agent which is: citric acid
Implementation Method 4
drying the aged catalyst
Data Source
AI summary
The invention refers to a process for rejuvenating a hydrotreating catalyst comprising a group VIB hydrogenation metal and/or a group VIII hydrogenation metal, which comprises the steps of: (a) regenerating the catalyst by contacting said catalyst with an oxygen containing gas at a temperature from about 300° C. to 550° C. to obtain a regenerated carbon-reduced catalyst, (b) impregnating the regenerated carbon-reduced catalyst with a solution which consists of a mixture of water and citric acid, (c) aging the impregnated catalyst for at least 6 hours and (d) drying the aged catalyst. The invention also refers to the rejuvenated catalyst obtained and its use for hydrotreating hydrocarbon feedstocks.