Multi-Metal Oxide Catalyst for Acrylonitrile Conversion and Selectivity
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Solution Overview
Problem
Existing catalysts for the ammoxidation of unsaturated hydrocarbons to unsaturated nitriles, such as propylene to acrylonitrile, suffer from suboptimal conversion rates and selectivity, necessitating improved catalyst compositions and processes.
Innovation Solution
A catalyst composition comprising a complex of catalytic oxides with specific relative ratios of molybdenum, bismuth, cerium, iron, chromium, and additional elements from groups A, B, and optionally C, optimized through precise ratios and phases, enhances the ammoxidation process by improving conversion and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts are used for ammoxidation of propylene, then the process can proceed, but conversion rates and selectivity to acrylonitrile are suboptimal
Solution Approach 1:
The patent employs a composite catalyst system combining multiple metal oxides (molybdenum, bismuth, cerium, iron, chromium) with specific promoters (groups A, B, and C elements) in precisely controlled ratios. This composite approach allows synergistic effects where each component contributes to different aspects of catalytic performance, achieving both high conversion and selectivity simultaneously.
Solution Approach 2:
The patent optimizes multiple parameters including the relative ratios of metal oxides (a:b:c:d:e:f:g=x:y:z), the inclusion of specific promoter elements from groups A, B, and C, and the phase composition (scheelite:β-MMoO4 ratio ≤ 0.3). These parameter optimizations enable the catalyst to achieve superior performance in both conversion and selectivity.
2Ease of manufacture
If catalyst composition is simplified, then manufacturing is easier, but performance in terms of conversion and selectivity deteriorates
Solution Approach 1:
The patent applies local quality by incorporating specific promoter elements (groups A, B, and C) in controlled amounts at specific positions within the catalyst structure. These promoters are added in precise ratios (e.g., group A elements at 0.01-2.0 times the sum of bismuth and cerium) to optimize local catalytic properties while maintaining overall manufacturability through a systematic formulation approach.
3Reliability
If catalyst composition is optimized with multiple elements and precise ratios, then selectivity and conversion improve, but device complexity increases
Solution Approach 1:
The patent segments the catalyst composition into distinct functional components: base metal oxides (molybdenum, bismuth, cerium, iron, chromium) and promoter groups (groups A, B, and C elements). This segmentation allows for systematic optimization where each segment can be independently selected and ratio-controlled, managing complexity through structured formulation while achieving high selectivity.
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 improved catalyst achieves higher overall conversion and selectivity in the production of unsaturated nitriles, such as acrylonitrile, by optimizing the catalyst's composition and phase ratios, leading to enhanced yield and efficiency in the ammoxidation process.
Implementation Method 1
Catalysts containing oxides of iron, bismuth and molybdenum, promoted with suitable elements, for use in the conversion (i.e., ammoxidation) of propylene at elevated temperatures in the presence of ammonia and a source of molecular oxygen
Implementation Method 2
conversion (i.e., ammoxidation) of propylene at elevated temperatures in the presence of ammonia and a source of molecular oxygen
Data Source
AI summary
The invention relates to catalyst compositions comprising a complex of catalytic oxides comprising molybdenum, bismuth, cerium, iron, chromium, at least one element of group A, at least one element of group B, and optionally at least one element of group C wherein the relative ratios of these elements are represented by Formula (1): Mo12BiaCebFecCrdAeBfCgOx. The invention also relates to a process for the ammoxidation of an olefin comprising reacting in the vapor phase at an elevated temperature and pressure the olefin with a molecular oxygen containing gas and ammonia in the presence of the catalyst composition.