Nitrogen-doped carbon-wrapped nickel catalyst for synthesis of higher alcohols by assembly of bioethanol and preparation method therefor
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Solution Overview
Problem
Existing nickel-based catalysts for converting bioethanol to higher alcohols suffer from excessive dehydrogenation, leading to C—C bond breakage and methanation, resulting in low catalytic efficiency.
Innovation Solution
A nitrogen-doped carbon-wrapped nickel catalyst is prepared by pyrolyzing a precursor of soluble nickel salt and polyacrylamide, forming Ni3N and a nitrogen-doped carbon layer to modify the electron structure of Ni, reducing its metallicity and enhancing catalytic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nickel-based catalyst is used for converting bioethanol to higher alcohols, then catalytic activity is improved, but excessive dehydrogenation occurs leading to C-C bond breakage and methanation
Solution Approach 1:
The patent modifies the electronic structure of nickel catalyst by changing compositional parameters (adding nitrogen dopant at controlled concentrations of 1-10 at%) and structural parameters (creating carbon-wrapped configuration), which alters the catalyst's dehydrogenation activity and selectivity to prevent excessive dehydrogenation while maintaining catalytic performance
Solution Approach 2:
The patent creates a composite catalyst system consisting of nitrogen-doped carbon-wrapped nickel particles, combining nickel metal with nitrogen-doped carbon material. This composite structure modifies the electronic properties of nickel and provides a stable framework that prevents excessive dehydrogenation and C-C bond breakage while maintaining high catalytic activity for higher alcohol synthesis
2Productivity
If nitrogen-doped carbon layer is formed around nickel particles, then metallicity is reduced and catalytic efficiency is enhanced, but preparation process becomes more complex
Solution Approach 1:
The patent employs preliminary action by using polyacrylamide as a sacrificial template and nitrogen source that is incorporated into the catalyst structure during the pyrolysis process. The polyacrylamide is mixed with nickel salt before pyrolysis, and upon heating, it decomposes to form the nitrogen-doped carbon layer around nickel particles, automatically creating the protective coating without requiring separate processing steps
Solution Approach 2:
The patent utilizes phase transition during pyrolysis (heating from ambient to 400-800°C) to transform the precursor mixture into the final nitrogen-doped carbon-wrapped nickel catalyst. The polyacrylamide undergoes thermal decomposition and carbonization to form the carbon-wrapped structure, while the nickel salt reduces to metallic nickel particles. This single thermal processing step achieves both the formation of nitrogen-doped carbon layer and the creation of active nickel sites
3Ease of manufacture
If polyacrylamide is used as precursor, then nitrogen doping and carbon wrapping are achieved simultaneously, but selectivity in forming C4+ higher alcohols decreases without optimal conditions
Solution Approach 1:
The patent optimizes multiple parameters including polyacrylamide to nickel salt molar ratio (0.5-8:1), pyrolysis temperature (400-800°C), and pyrolysis time (1-6 hours) to achieve the optimal balance between nitrogen doping concentration, carbon layer formation, and catalytic selectivity for C4+ higher alcohol production
Solution Approach 2:
The patent creates local quality differences by forming a nitrogen-doped carbon layer with specific nitrogen concentration (1-10 at%) and structural characteristics around the nickel particles. This localized modification of the catalyst surface provides enhanced selectivity for C-C coupling reactions while maintaining the overall catalytic activity, thereby improving C4+ higher alcohol formation
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 high selectivity and stability for synthesizing isomeric higher alcohols with carbon atoms of 4-16, maintaining high conversion rates and yields even after repeated use.
Implementation Method 1
forming Ni3N and a nitrogen-doped carbon layer to modify the electron structure of Ni, reducing its metallicity and enhancing catalytic efficiency
Implementation Method 2
A nitrogen-doped carbon-wrapped nickel catalyst is prepared by pyrolyzing a precursor of soluble nickel salt and polyacrylamide
Data Source
AI summary
The present invention relates to a nitrogen-doped carbon-wrapped nickel catalyst for synthesis of higher alcohols by assembly of bioethanol and a preparation method therefor. The preparation method includes the following steps: S1, subjecting a soluble nickel salt and polyacrylamide to stirring with water, completely dissolving and then drying to obtain a precursor, where a molar ratio of the soluble nickel salt to polyacrylamide is 1:(0.5-8); and S2, subjecting the precursor to pyrolysis in an inert atmosphere at 300° C.-800° C. for 1-6 hours to obtain the nitrogen-doped carbon-wrapped nickel catalyst. The catalyst prepared by the method of the present invention has an active phase with high dispersity which enables synthesis of higher alcohols by efficient assembly of small molecules, and has relatively high stability which can still maintain high conversion rate and high yield for organic phase after 10 times of repeated use.