Dual Catalyst Bed Hydrocracking for Distillate Yield
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Solution Overview
Problem
Current hydrocracking processes face challenges in efficiently producing distillate fuels with improved properties and yields, particularly due to differences in reaction conditions required for hydrocracking and aromatic saturation catalysts, leading to suboptimal equipment usage and product distribution.
Innovation Solution
Incorporating a noble metal aromatic saturation catalyst in conjunction with a base metal hydrocracking catalyst in a single reaction stage, allowing for simultaneous aromatic saturation and hydrocracking without intermediate separation, which reduces equipment footprint and enhances distillate fuel yield and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single reaction stage with both aromatic saturation catalyst and hydrocracking catalyst is used, then equipment footprint is reduced and process efficiency is improved, but the conflicting reaction conditions required by the two catalyst types cannot be simultaneously optimized
Solution Approach 1:
The catalyst system is segmented into two distinct beds: a first bed containing aromatic saturation catalyst (e.g., Pt/Al2O3) and a second bed containing hydrocracking catalyst (e.g., NiMo/USY). This segmentation allows each catalyst to operate under its optimal conditions while being part of the same reaction stage, resolving the contradiction between equipment simplification and condition compatibility.
Solution Approach 2:
The solution transitions from a single homogeneous catalyst environment to a multi-zone catalytic environment with distinct beds. By adding the dimension of spatial separation within the reactor, the system can accommodate different temperature, pressure, and chemical environments for each catalyst type, thereby maintaining adaptability while improving productivity.
2Quantity of substance
If conventional hydrocracking conditions are used, then hydrocracking activity is maintained, but distillate fuel yield is limited due to lack of aromatic saturation
Solution Approach 1:
Aromatic saturation is performed as a preliminary action before hydrocracking. The first catalyst bed saturates aromatic compounds in the feedstock, which then facilitates more efficient hydrocracking in the second bed. This preliminary aromatic saturation increases distillate fuel yield by reducing the severity required for hydrocracking, thereby improving both quantity and productivity.
3Productivity
If hydrocracking severity is increased to improve conversion, then fuel yield increases, but product quality such as cetane number and isomerization decreases
Solution Approach 1:
The two-catalyst system enables continuous beneficial actions: aromatic saturation occurs continuously in the first bed, followed by hydrocracking in the second bed. This continuous dual-action process maintains high conversion rates while preserving product quality, as the aromatic saturation prepares the feed for milder hydrocracking conditions that produce higher quality distillates with better cetane numbers and isomerization.
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 increases distillate fuel yield by 0.25 to 5.0 vol% through 'volume swell' and improves product properties such as cetane number and isomerization, while reducing the severity of hydrocracking conditions, thus enhancing the overall efficiency and commercial value of the process.
Implementation Method 1
exposing a feedstock to a base metal hydrocracking catalyst and a noble metal aromatic saturation catalyst in a single reaction stage
Implementation Method 2
hydrocracking of hydrocarbon feedstocks is often used to convert lower value hydrocarbon fractions into higher value products
Data Source
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AI summary
Systems and methods are provided for producing an improved product slate during hydrocracking of a feedstock that results in production of naphtha and distillate fuels. The methods can include use of stacked beds and/or sequential reactors so that a feedstock is exposed to suitable catalysts under hydrocracking conditions and aromatic saturation conditions. The catalyst for performing the aromatic saturation process can be a catalyst including a Group VIII noble metal, such as Pt, Pd, or a combination thereof, while the hydrocracking catalyst can include Group VIB and Group VIII non-noble metals.