Multi-Metal Catalyst for Butadiene Selectivity
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Solution Overview
Problem
The oxidative dehydrogenation of n-butene to produce 1,3-butadiene faces challenges due to side reactions and the difficulty in synthesizing and reproducing catalysts with high selectivity and yield, while also being cost-effective.
Innovation Solution
A method for producing a dehydrogenation catalyst comprising zinc, iron, cobalt, magnesium, and optionally calcium, with specific mole ratios and pH control, which allows for high zinc recovery and reduced zinc usage, enhancing the catalyst's selectivity and stability for n-butene conversion to 1,3-butadiene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional zinc ferrite catalyst is used, then the catalyst is easy to synthesize and reproduce, but the activity in producing 1,3-butadiene is low
Solution Approach 1:
The patent creates a composite catalyst system by substituting zinc ferrite with other metals (such as manganese, cobalt, nickel, copper, or their oxides/carbonates/chlorides) to form a multi-metallic catalyst composition. This composite approach combines the ease of synthesizing zinc ferrite with the enhanced catalytic activity of alternative metals, resolving the contradiction between manufacturability and productivity.
2Manufacturing precision
If zinc content in catalyst is increased, then selectivity to 1,3-butadiene is improved, but the cost of catalyst increases and zinc recovery becomes difficult
Solution Approach 1:
The patent optimizes zinc content to a specific range (0.1-0.5 moles relative to 1 mole of iron) rather than using excessive zinc, and incorporates metal substitution strategies that allow for better zinc recovery. The controlled zinc content combined with alternative metals maintains high selectivity while reducing zinc loss and improving economic viability.
Solution Approach 2:
The patent changes the zinc-to-iron mole ratio parameter to an optimized range (0.1-0.5) instead of using high zinc content. This parameter optimization maintains catalytic selectivity while reducing zinc consumption and cost, directly addressing the contradiction between selectivity and material loss.
3Temperature
If oxidative dehydrogenation reaction is performed, then thermodynamically favorable reaction with stable water product is achieved, but side reactions such as complete oxidation occur
Solution Approach 1:
The patent modifies the local quality of the catalyst by incorporating specific metals (manganese, cobalt, nickel, copper or their compounds) that create localized active sites with different properties. These localized modifications suppress complete oxidation side reactions while maintaining the desired oxidative dehydrogenation pathway, allowing the reaction to proceed at lower temperatures with 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 catalyst achieves greater than 75% n-butene conversion and 91% selectivity to 1,3-butadiene, with high zinc recovery and reduced production costs, maintaining performance for over 40 hours at 320°C to 400°C.
Implementation Method 1
The oxidative dehydrogenation reaction of n-butene (1-butene, trans-2-butene, cis-2-butene) is a reaction for forming 1,3-butadiene and water by reacting n-butene with oxygen
Implementation Method 2
adding base to the mixture to form a slurry having a pH of 7 to 8.5
Implementation Method 3
aging the slurry at a temperature of greater than or equal to 40°C while agitating; filtering a precipitate from the aged slurry to collect a catalyst precursor
Data Source
AI summary
A method of making a dehydrogenation catalyst can comprise: combining precursors in water to form a mixture; adding base to the mixture to form a slurry having a pH of 7 to 8.5; aging the slurry at a temperature of greater than or equal to 40°C while agitating; filtering a precipitate from the aged slurry to collect a catalyst precursor; drying and calcining the catalyst precursor to form the catalyst; wherein the catalyst has the formula (I) FeZnaCobMgcCadCleMfOx (I) wherein the amounts are in mole ratios relative to 1 mole of iron, "a" is 0.07 to 0.7 moles; "b" is 0.01 to 0.20 moles; "c" is less than or equal to 0.40 moles; "d" is less than or equal to 0.40 moles; "e" is less than or equal to 0.10 moles; and "f ' is less than or equal to 0.20 moles.