Mo-Bi-Nb Composite Catalyst for One-Step Acrylic Acid Production
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Solution Overview
Problem
Conventional two-step processes for producing (meth)acrylic acid from propylene using Mo-Bi based and Mo-V based catalysts result in low yields and require complex reactor systems, with issues of hotspot formation and yield degradation due to exothermic reactions.
Innovation Solution
A Mo-Bi-Nb based composite metal oxide catalyst is used in a one-step process to produce (meth)acrylic acid directly from propylene, eliminating the need for a second oxidation step and minimizing hotspot issues through efficient heat control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a two-step process using Mo-Bi based catalyst followed by Mo-V based catalyst is used to produce (meth)acrylic acid, then the production process can be completed, but the overall yield is low and the reactor system becomes complex
Solution Approach 1:
The patent combines the functions of two separate catalysts (Mo-Bi for acrolein production and Mo-V for acrylic acid production) into a single integrated catalyst system. The multi-metal oxide catalyst contains both Mo-Bi components and Mo-V components, allowing it to perform both oxidation steps sequentially within one reactor, thereby simplifying the reactor system while improving overall yield.
Solution Approach 2:
The invention creates a universal catalyst that performs multiple functions: it first catalyzes the oxidation of propylene to acrolein, then continues to catalyze the oxidation of acrolein to acrylic acid. This multi-functional catalyst eliminates the need for separate catalysts and reactors for each step, resolving the contradiction between productivity and device complexity.
2Quantity of substance
If conventional Mo-Bi based catalyst is used in the first step, then (meth)acrolein is produced as main product, but (meth)acrylic acid yield is limited to 10% or less
Solution Approach 1:
The patent employs a composite metal oxide material that integrates the active components of both Mo-Bi catalyst (for acrolein production) and Mo-V catalyst (for acrylic acid production). This composite structure allows the catalyst to first produce acrolein as the main product, then further oxidize it to acrylic acid, thereby increasing the final acrylic acid yield beyond the 10% limitation of conventional single-function catalysts.
3Productivity
If exothermic oxidation reactions are performed in conventional catalyst systems, then the oxidation process proceeds, but hotspot formation occurs leading to yield degradation
Solution Approach 1:
The patent modifies the physical and chemical parameters of the catalyst system by incorporating specific metal oxides (Mo, Bi, V, Nb) in controlled ratios and particle size distributions. These parameter changes affect the heat distribution and reaction kinetics, allowing the exothermic oxidation to proceed efficiently while preventing localized overheating and hotspot formation, thus maintaining production stability.
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 Mo-Bi-Nb catalyst achieves high selectivity and yield of (meth)acrylic acid, stabilizing production over time by controlling catalyst activity and heat management, thereby overcoming the limitations of conventional two-step processes.
Implementation Method 1
a Mo—Bi—Nb based composite metal oxide (multi-metal oxide), and a method for producing (meth)acrylic acid from propylene or the like by using the Mo—Bi—Nb based composite metal oxide as a catalyst
Implementation Method 2
propylene or the like is oxidized by oxygen, inert gas for dilution, water steam and a certain amount of a catalyst, so as to produce (meth)acrolein as a main product
Data Source
AI summary
The present invention provides a Mo—Bi—Nb based composite metal oxide (with the proviso that Te is not included); a method for producing (meth)acrylic acid from at least one reactant selected from the group consisting of propylene, propane, isobutylene, t-butyl alcohol and methyl-t-butyl ether, in which a Mo—Bi—Nb based composite metal oxide (with the proviso that Te is not included) is used as a catalyst; and a reactor used for producing (meth)acrylic acid from at least one reactant selected from the group consisting of propylene, propane, isobutylene, t-butyl alcohol and methyl-t-butyl ether, in which a Mo—Bi—Nb based composite metal oxide (with the proviso that Te is not included) is used as a catalyst. Further, the present invention provides a method for producing the (meth)acrylic acid without any additional process of converting (meth)acrolein into (meth)acrylic acid.