Ti-Si-P Composite Catalyst for Ethylenimine Synthesis
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Solution Overview
Problem
Existing catalysts for synthesizing ethylenimine have low specific surface area and short service life, leading to low activity and selectivity at high reaction temperatures, resulting in increased by-products and reduced ethylenimine selectivity.
Innovation Solution
A catalyst comprising a composite oxide carrier with titanium, silicon, and phosphorus elements, loaded with magnesium, iron, and cesium ions, prepared using a method involving silicon oxide, titanium oxide, and ammonium phosphate, followed by fluoridation and roasting, to achieve a high specific surface area and large pore volume, allowing for efficient intramolecular dehydration at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a roast step at high temperature (≥600°C) is used to prepare catalyst with high specific surface area, then the specific surface area increases, but the local high temperature from strong exothermic reaction significantly decreases the specific surface area, resulting in decreased activity and selectivity
Solution Approach 1:
The patent changes the roasting temperature parameter from conventional high temperature (≥600°C) to a lower temperature range (500-600°C), and introduces a two-stage roasting process with controlled temperature rates. This parameter optimization reduces excessive exothermic heat, prevents over-roasting that destroys surface area, and maintains catalyst activity and selectivity while achieving high specific surface area (≥40 m²/g).
Solution Approach 2:
The patent uses a composite oxide carrier system comprising titanium oxide, silicon oxide, and phosphorus oxide in specific ratios (TiO2:SiO2:P2O5 = 70:20:10 to 90:5:5). This composite structure provides both high surface area and thermal stability, where each component contributes different properties: TiO2 provides surface area, SiO2 provides structural stability, and P2O5 enhances catalytic activity. The composite material resolves the contradiction by combining materials that work synergistically to maintain surface area and activity simultaneously.
2Speed
If the reaction temperature is increased above 400°C to speed up the reaction, then the reaction rate increases, but the deamination and intramolecular condensation reactions occur easily, increasing by-products and decreasing selectivity for ethylenimine
Solution Approach 1:
The patent optimizes the reaction temperature parameter to a specific range (370-400°C) and introduces a two-stage temperature control strategy: initial heating to 370-380°C for 1-2 hours to activate catalyst and control reaction, then raising to 390-400°C for 2-4 hours to complete conversion. This controlled temperature profile achieves high reaction rate while minimizing unwanted side reactions, maintaining ethylenimine selectivity above 90% and conversion rate above 35%.
Solution Approach 2:
The patent implements continuous catalytic action through a two-stage reaction process with controlled temperature and time parameters. The first stage (370-380°C, 1-2 hours) establishes optimal catalytic activity, and the second stage (390-400°C, 2-4 hours) maintains activity while completing conversion. This continuous controlled action ensures high selectivity throughout the reaction process, preventing by-product formation that would occur with single-stage high-temperature processing.
3Power
If the specific surface area is increased to improve catalytic activity, then the activity increases, but a roast step at high temperature is needed which decreases the specific surface area due to strong exothermic reaction
Solution Approach 1:
The patent optimizes the roasting temperature parameter from conventional high temperature to a controlled range (500-600°C) with specific heating rates (1-3°C/min). This parameter change reduces excessive exothermic heat generation during roasting, preventing the destruction of surface area. The optimized process achieves high specific surface area (≥40 m²/g) while maintaining catalytic activity through controlled thermal treatment.
Solution Approach 2:
The patent employs a composite oxide carrier (TiO2-SiO2-P2O5) where each component contributes specific properties: TiO2 provides high surface area and catalytic activity, SiO2 provides structural stability and prevents sintering, and P2O5 enhances acid-base properties and catalytic performance. This composite material structure resolves the contradiction by combining materials that work synergistically to maintain both high surface area and high activity without requiring excessive roasting temperature.
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 exhibits high selectivity and long service life, with monoethanolamine conversion rates up to 38% and ethylenimine selectivity up to 95% at 370°C, maintaining constant activity for 1,000 hours, and can be used for various amino alcohols.
Implementation Method 1
A catalyst for synthesizing ethylenimine by using amino alcohol as a raw material
Implementation Method 2
the catalyst exhibits high selectivity and long service life, with monoethanolamine conversion rates up to 38% and ethylenimine selectivity up to 95% at 370°C
Data Source
AI summary
The present invention relates to a catalyst for synthesizing ethylenimine as well as a preparation method and application thereof. The related catalyst comprises a carrier and metal ions loaded on the carrier; the carrier is a composite oxide comprising titanium, silicon and phosphorus elements; the metal ions are magnesium ions, iron ions and cesium ions; the molar ratio of the magnesium ions to the iron ions to the cesium ions is (1-10):1:0.1; the mass of all metal ions is 0.5-10 percent of that of the carrier. In the related preparation method, a catalyst precursor is roasted at the temperature of 350-650° C., so that the catalyst is obtained; the catalyst precursor is the mixture of the carrier, soluble salt of magnesium, soluble salt of iron and soluble salt of cesium. The present invention also provides the application of the catalyst to synthesis of the ethylenimine by using amino alcohol as the raw material. Compared with a common catalyst which has the requirement on the temperature of over 400° C., the catalyst of the present invention obviously reduces the reaction temperature. The prepared catalyst can catalyze the intramolecular dehydration reaction of the amino alcohol and has relatively excellent selectivity.