Nickel Catalyst Sulfur Absorption in Ammonia Streams
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Solution Overview
Problem
The presence of sulfur in ammonia streams from catalytic refining processes poses a challenge for their utilization in hydrogen production, as sulfur acts as a poison for downstream catalysts, leading to costly disposal and inefficient hydrogen recovery.
Innovation Solution
A nickel-containing catalyst with a total nickel content of 10 wt% to 70 wt% supported on carrier materials like alumina, silica, or titania is used to absorb sulfur from ammonia streams, producing a sulfur-free ammonia stream suitable for hydrogen production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sulfur-containing ammonia stream is used directly in reforming stage, then hydrogen production can proceed, but downstream catalysts (nickel-based reforming catalysts and water-gas shift catalysts) are poisoned by sulfur
Solution Approach 1:
A nickel-containing catalyst is introduced as an intermediary substance between the sulfur-containing ammonia stream and the downstream catalysts. This intermediary catalyst absorbs and retains sulfur through chemisorption, preventing sulfur from reaching and poisoning the reforming and water-gas shift catalysts, thus enabling both hydrogen production and catalyst protection
Solution Approach 2:
The harmful sulfur content in the ammonia stream is converted into a beneficial feature by using it as a sulfur source that can be selectively absorbed and retained by the nickel catalyst. The sulfur that would otherwise poison downstream catalysts is instead captured and held on the nickel catalyst surface, transforming a harmful impurity into a controlled component
2Reliability
If sulfur-containing ammonia stream is disposed of instead of utilized, then catalyst poisoning is avoided, but disposal costs increase and hydrogen recovery efficiency decreases
Solution Approach 1:
Instead of discarding the sulfur-containing ammonia stream, the invention recovers the sulfur by having it absorbed and retained on the nickel catalyst. The sulfur is not permanently discarded but rather transferred to and held on the catalyst, allowing the ammonia to be utilized for hydrogen production while the sulfur is sequestered on the catalyst surface
Solution Approach 2:
The nickel-containing catalyst serves a dual function: it catalyzes the reforming reaction to produce hydrogen while simultaneously serving as a sulfur absorbent that protects other catalysts. The system uses its own catalyst to perform the sulfur removal function, eliminating the need for separate purification equipment
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 process effectively removes both hydrogen sulfide and organic sulfur from ammonia streams, enabling the reuse of sulfur-containing ammonia in hydrogen production, reducing disposal costs and increasing hydrogen recovery efficiency.
Implementation Method 1
passing said stream through a fixed bed of sulfur absorbent in a sulfur absorber and withdrawing a sulfur-free ammonia stream, wherein said sulfur absorbent is a catalyst having a total nickel content in reduced form
Data Source
AI summary
Process for the removal of organic and/or inorganic sulfur from an ammonia stream by passing said stream through a fixed bed of sulfur absorbent in a sulfur absorber and withdrawing a sulfur-free ammonia stream, wherein said sulfur absorbent is a catalyst having a total nickel content in reduced form in the range 10 wt % to 70 wt % with the balance being a carrier material selected from the group of alumina, magnesium alumina spinel, silica, titania, magnesia, zirconia and mixtures thereof.