HCFO Refrigerant Purification via Low-Temperature Neutralization
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Solution Overview
Problem
Current processes for purifying hydrochlorofluoroolefin refrigerants like R1233zd-E struggle to remove HF and HCl from organic-rich streams without losing the desired refrigerant or increasing unwanted by-products like trifluoropropyne, especially when the refrigerant is not volatile enough to stay in the vapor phase, requiring high temperatures or costly vacuum conditions.
Innovation Solution
A method involving mixing the crude R1233zd-E stream with a caustic stream at a pH greater than 10 and temperatures less than 50°C, converting HF and HCl to salts, allowing for separation into an organic phase and an aqueous phase, followed by drying and distillation to produce purified R1233zd-E, while minimizing trifluoropropyne production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperatures or vacuum conditions are used to remove HF and HCl from the crude stream, then the acid removal efficiency is improved, but the refrigerant loss increases and production cost increases
Solution Approach 1:
The invention changes the temperature parameter from high temperature (conventional) to low temperature (less than 50°C, preferably less than 20°C) to resolve the contradiction. By conducting the neutralization reaction at low temperatures, the refrigerant remains in liquid phase and is not lost, while HF and HCl are effectively removed through chemical neutralization with aqueous base. This parameter change eliminates the need for vacuum conditions and prevents refrigerant evaporation losses.
Solution Approach 2:
The invention introduces an intermediary substance (aqueous base such as NaOH or KOH solution) to facilitate the removal of HF and HCl. The base reacts with the acids to form water-soluble salts that can be separated from the organic refrigerant phase. This intermediary enables effective acid removal at low temperatures without requiring vacuum conditions, thus preventing refrigerant loss while achieving purification.
2Manufacturing precision
If high temperatures are used to purify the crude stream, then the acid removal efficiency is improved, but the formation of unwanted by-products like trifluoropropyne increases
Solution Approach 1:
The invention changes the temperature parameter from high temperature to low temperature (less than 50°C, preferably less than 20°C) to prevent the formation of trifluoropropyne by-product. The low temperature conditions suppress unwanted side reactions while still enabling effective neutralization of HF and HCl through chemical reaction with the aqueous base, thus achieving acid removal without increasing harmful by-product formation.
3Productivity
If the refrigerant is kept in vapor phase for purification, then the separation efficiency is improved, but the energy consumption increases
Solution Approach 1:
The invention inverts the conventional approach by keeping the refrigerant in liquid phase rather than vapor phase during purification. The crude refrigerant stream is contacted with aqueous base in liquid-liquid extraction mode, allowing HF and HCl to be neutralized and removed. This inversion eliminates the need for vaporization and condensation steps, significantly reducing energy consumption while maintaining effective separation through phase separation of the aqueous and organic layers.
4Manufacturing precision
If aqueous base is used to remove HF and HCl, then the acid removal efficiency is improved, but the refrigerant may be lost through solubility in the aqueous phase
Solution Approach 1:
The invention uses liquid-liquid extraction where the crude refrigerant stream is contacted with aqueous base. The HF and HCl are extracted into the aqueous phase as water-soluble salts, while the organic refrigerant remains in the organic phase. The two phases are then separated by decantation or phase separation, allowing the refrigerant to be recovered with minimal loss. This extraction approach selectively removes acids while preserving the refrigerant in the organic phase.
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
Effectively reduces HF and HCl levels in the refrigerant stream without significantly altering the organic constituents, minimizing trifluoropropyne formation and other unwanted products, and allows for easy disposal of the aqueous phase with trace amounts of organics.
Implementation Method 1
contacting the crude HFCO stream with an aqueous base stream... the base reacts with the at least one of HF or HCl forming a salt
Implementation Method 2
allowing for separation into an organic phase and an aqueous phase
Data Source
AI summary
Disclosed is a step in the purification process of hydrochlorofluoroolefin refrigerants that are made from processes wherein 1,1,3,3 tetrachloropropene (R1230za) or 1,1,1,3,3-pentachloropropane (R240fa) is reacted with HF in excess. The purification process employs a cold-temperature reaction with a base to remove the HF and any HCl. The process prevents an increase in unwanted organic side-products, particularly trifluoropropyne (TPS), and simultaneously does not reduce the amount of the desired hydrochlorofluoroolefin refrigerant produced. The process also can have an optional step whereby hydrochlorofluoroolefin refrigerant and other organics are removed from aqueous process stream or streams resulting from the reaction with the base. The organics removed can be recycled. This optional step advantageously can increase the yield of the desired refrigerant, while decreasing the environmental load of the plant, by purifying the resulting aqueous process streams.