15 results about "Ultra high purity" patented technology

This application discloses a method for preparing ultra-high purity citric acid monohydrate based on supercritical CO2, belonging to the field of citric acid preparation technology. The method includes the following steps: dissolving citric acid monohydrate in an organic solvent to prepare a citric acid solution; spraying the citric acid solution into a supercritical CO2 environment to crystallize the citric acid using the supercritical anti-solvent effect; performing dynamic washing with pure supercritical CO2; and obtaining ultra-high purity citric acid monohydrate crystals after depressurization and drying. The citric acid monohydrate product prepared by this method has high purity, high light transmittance, low total metal ion content, controllable crystal habit, and low organic solvent residue, meeting the stringent requirements of high-end applications such as electronic and pharmaceutical grades.

Processes for producing two CO2 streams having different purities, including one stream comprising ultra high purity CO2. The processes incorporate a second fractionation column in a CO2 fractionation process. The bottoms stream from the first cryogenic fractionation column is sent to the second CO2 fractionation column. The second CO2 fractionation column can produce ultra high purity CO2. The bottoms stream from the first column can be divided and a portion of the bottoms stream can be recovered as a second CO2 product stream having a lower purity than the purity of the product stream.

This invention belongs to the field of wet electrolytic refining technology for recycled lead, and provides a method for electrolytically preparing ultra-high purity lead. It involves constructing a 1-hydroxyethylidene-1,1-diphosphonic acid-modified lead carbonate seed layer on the cathode plate surface, combined with a bypass impurity removal unit to continuously remove impurity ions from the electrolyte, and then using staged current density electrolysis to ensure uniform nucleation and stable deposition of lead on the cathode surface. The resulting cathode lead has a purity of not less than 99.996 wt%, and the deposited layer is dense, flat, and has a low risk of inclusions. This method solves the problems of difficulty in balancing high-throughput deposition and ultra-high purity, as well as the difficulty in synchronizing seed layer adhesion stability and pollution control in existing processes. It is suitable for the high-value preparation of recycled lead from waste lead-acid batteries.

The application belongs to the technical field of phosphorus chemical industry, and provides a preparation method of high-purity urea phosphate. The preparation method comprises the following steps: (1) preheating wet-process phosphoric acid, preparing urea aqueous solution and preheating, and preparing calcium hydroxide suspension; (2) adding the calcium hydroxide suspension into the wet-process phosphoric acid drop by drop, keeping the pH of the system at 0.8-1.8, and generating calcium phosphate nanocrystals in situ; (3) adding the urea aqueous solution into the calcium phosphate nanocrystals for reaction, simultaneously starting the nanofiltration membrane system for online circulation impurity removal, and obtaining a reaction liquid; (4) constant-temperature static setting crystallization of the reaction liquid; and (5) separation, washing and drying to obtain the high-purity urea phosphate. The preparation method uses the wet-process phosphoric acid as a raw material, realizes one-step high-purity crystallization through acid in-situ calcium phosphate nanocrystal induction and reaction-nanofiltration collaborative impurity removal, and has no organic additive residue; the high-purity urea phosphate with super-high purity, regular crystal form and extremely low impurities can be prepared, and is suitable for high-end application scenarios.

This application belongs to the field of electronic gas purification technology, specifically relating to a method for removing R133a from hexafluoropropane. Hexafluoropropane feedstock containing R133a impurities is passed into an adsorption column packed with a modified adsorbent, and high-purity hexafluoropropane is obtained through adsorption. The modified adsorbent is any one of modified molecular sieves, modified metal-organic framework materials, or modified mesoporous silica. This application improves the specific adsorption selectivity of the adsorbent for R133a impurities by modifying adsorbents such as molecular sieves, metal-organic framework materials, and mesoporous silica. It can stably remove R133a impurities from the hexafluoropropane feedstock at a volume fraction of 0.5%~1% to an extremely low level of less than 0.5 ppm, meeting the ultra-high purity requirements of hexafluoropropane in fields such as semiconductors.

This invention relates to the field of isomer separation of organic alcohols and discloses a method for preparing ultra-high purity alcohols. The method includes the following steps: (1) under the action of an acidic catalyst, a first organic alcohol raw material containing a second organic alcohol and an acylating agent are subjected to an esterification reaction, followed by an optional salt formation reaction to obtain a solid material containing a first crude ester salt crystal and a second crude ester salt crystal; (2) the solid material containing the first crude ester salt crystal and the second crude ester salt crystal is dissolved in solvent I for recrystallization to obtain a first refined ester salt crystal; (3) the first refined ester salt is subjected to a hydrolysis reaction in an alkaline aqueous solution; wherein the second organic alcohol is an isomer of the first organic alcohol. This method can simply and efficiently separate isomers to obtain ultra-high purity alcohol compounds.

Processes for producing two CO2 streams having different purities, including one stream comprising ultra high purity CO2. The processes incorporate a second fractionation column in a CO2 fractionation process. The bottoms stream from the first cryogenic fractionation column is sent to the second CO2 fractionation column. The second CO2 fractionation column can produce ultra high purity CO2. The bottoms stream from the first column can be divided and a portion of the bottoms stream can be recovered as a second CO2 product stream having a lower purity than the purity of the product stream.

This invention belongs to the field of pharmaceutical crystallization technology and substance separation and purification. It discloses a method for directly crystallizing large-particle, high-purity ergothioneine crystals from fermentation broth, and the resulting large-particle, high-purity ergothioneine crystals. The method uses ergothioneine fermentation broth as the starting material, dissolving it in a specific crystallization solvent, and then sequentially undergoing two programmed cooling and crystal growth processes to directly crystallize and obtain the target product. This method, through the synergistic selection of the solvent system and control of crystallization kinetics, simultaneously completes the purification and crystallization of ergothioneine in a single step, eliminating the complex multi-step pretreatment and purification units found in existing technologies. The obtained product has high purity (≥99.992%), good flowability, particle size >200μm, and angle of repose <25°, possessing ultra-high purity, ideal physical morphology, and excellent flowability, and can be directly used in downstream formulation production. This invention features a very simple process flow, high production efficiency, low cost, and superior overall product performance, demonstrating significant industrial application value.

The application discloses a kind of synthetic oligonucleotide B type CPG purification preparation process, it is related to oligonucleotide preparation technical field, the application is by using hydrophobic interaction chromatography purification combined online acid treatment as core pre-purification step, fundamentally solve the problem of insufficient separation ability to structure similar impurities, utilize the strong hydrophobic DMT protecting group carried by full-length target chain DMT-on state, and the short chain failure sequence DMT-off that this group is missing is different in the retention behavior on hydrophobic interaction chromatography filler, realize efficient, high selectivity separation, this process is completed under high salt loading condition, DMT-off impurity is directly flowed through, and DMT-on target molecule is strongly retained, by directly pumping acidic low salt eluent into chromatographic column, DMT protecting group is acidolysis cut with full-chain DNA on column, so that target DNA molecule is converted into DMT-off state and is eluted under low salt condition and is recovered, realize the effective removal of impurities near main peak, lay the foundation for finally obtaining ultrahigh purity product.

This application provides an ultrapure titanium dioxide, its preparation method, and its application. The method includes the following steps: S1: Dissolving an inorganic titanium source and a composite weakly polydentate dynamic coordination molecule in an inert organic solvent to obtain a composite precursor solution; wherein the composite weakly polydentate dynamic coordination molecule contains two or more reversible coordination functional groups; S2: Adding water to the composite precursor solution to form a titanium-oxygen network precursor; S3: Performing solvothermal treatment on the titanium-oxygen network precursor to induce crystallization, obtaining a crystallization intermediate; S4: Performing a two-stage heat treatment on the crystallization intermediate to obtain ultrapure titanium dioxide. Through the above method, titanium dioxide materials with both ultra-high purity and strong photocatalytic activity can be prepared without relying on external ion doping or unstable post-reduction treatment.

The application discloses a preparation method of dimethylphenylsulfonium triflate, and the preparation method is that benzyl sulfide and methyl triflate are used to synthesize dimethylphenylsulfonium triflate, and then dimethylphenylsulfonium triflate products are obtained through crystallization, filtration, washing and drying, the molar ratio of benzyl sulfide and methyl triflate is 1:1.3-1.5; the prepared product sample has a purity of 99.89%, the content of metal impurities is controlled to be within 60 ppb, and only two kinds of impurities are detected, in addition, the prepared sample is more conducive to obtaining ultrahigh-purity products, and further recrystallization can obtain ultrahigh-purity products with a purity of more than 99.96% and metal impurities within 40 ppb.

The application belongs to the technical field of silicon carbide powder preparation, and relates to high-purity silicon carbide powder for ceramics and a preparation process thereof. The preparation process comprises the following steps: S1: adding an ethanol aqueous solution into a reaction kettle, adjusting the pH to 2.5-3.0, adding a silicon source, reacting, adding a polyphenol compound, heating, mixing, cooling, and obtaining a homogeneous sol; S2: under the assistance of ultrasonic waves, uniformly dispersing fluorine-containing polymer nanoemulsion in the homogeneous sol, and then spray drying to obtain precursor microsphere powder; and S3: under an inert atmosphere, placing the precursor microsphere powder in an atmosphere furnace, performing gradient heating treatment, and then, under an air atmosphere, heat-treating at 550-600 DEG C to obtain high-purity silicon carbide powder. The high-purity silicon carbide powder prepared by the method has the advantages of ultrahigh purity, uniform and controllable submicron particle size, excellent dispersibility and high sintering activity.

The present invention provides a method for manufacturing ultra-high purity ethylene carbonate, comprising: a step of esterifying ethylene oxide with carbon dioxide in the presence of a catalyst to produce ethylene carbonate; a DEG removal step of converting a byproduct of the esterification reaction, diethylene glycol (DEG), into monoethylene glycol (MEG) using pseudo-boehmite; and an impurity removal step of performing vacuum distillation on a product of the DEG removal step to remove impurities including MEG converted from DEG and moisture.