Method for preparing high specific surface area chromium series fluorating catalyst former body chromic oxide

Abstract

The invention relates to a preparation method for precursor chromic oxide of a chromic fluorination catalyst with high specific surface area, which is characterized by comprises the following steps of: completely dissolving an organic addition agent which can be a polyglycol-series PEG1000-6000, or nonionic surface active agents Tween40, Tween80, or a cation surface active agent dodecyl cetyl trimethyl ammonium bromide in soluble chromic salt solution, controlling the weight ratio of the organic addition agent and the soluble chromic salt to be 0.1: 1 to 0.8: 1, and precipitating by a precipitator under stirring condition, filtering, washing and drying. By adding the organic additive, the method effectively improves the specific surface area of Cr2O3 question mark nH2O (n is less than 3 and more than 0) and has simple and easily operated preparation process and good experimental reproducibility. The prepared compound can be used for producing the fluorination catalyst of HFCs which is the substitute of Freon in a gas phase method after high temperature roasting and activation.

Description

technical field [0001] The invention relates to a high specific surface area fluorination catalyst precursor Cr 2 o 3 ·nH 2 The preparation method of O(0<n≤3). In particular, it relates to the preparation method of the fluorination catalyst precursor used in the gas-phase hydrogen fluoride fluorination to produce Freon substitute hydrofluorocarbons. It is a precipitant for the preparation of the fluorination catalyst precursor Cr 2 o 3 improvement of. Background technique [0002] Chromium-based catalyst precursor Cr currently used in gas phase production of Freon substitute hydrofluorocarbons 2 o 3 ·nH 2 The common preparation method of O(0<n<3) is the precipitation method. With NaOH, KOH, (NH 4 ) 2 CO 3 , ammonia water and other precipitants to precipitate chromium nitrate hydrate, chromium trichloride, chromium alum and other soluble chromium salts to form chromium hydroxide catalyst, filter, wash with water, and dry at 100-200 ° C to become Cr 2 o 3...

AI Technical Summary

Problems solved by technology

Chinese patent CN1408476 describes a high-activity long-acting fluorination catalyst and its manufacturing method. It adopts the precipitation method to configure the soluble salt of the active component (which can be nitrate, sulfate, chloride, etc.) into a solution of a certain concentration. At 100°C with precipitant (NaOH, KOH, (NH 4 ) 2 CO 3 , ammonia, etc.) reaction, control the final pH value between 6.5~9.5, this method must strictly control the pH value, the process is complicated, and the steps are numerous

Chinese patent CN1408476 mentions that the specific surface area of ​​the catalyst precursor chromium oxide prepared by precipitation method is greater than 200m 2 / g, but there is no specific data in the patent, according to our experimental results, the specific surface area is basically 100m 2 Below / g, and poor experimental reproducibility

The specific surface area of ​​the chromium oxide obtained by these methods is not completely satisfactory, so it is necessary to find a method to effectively improve the Cr 2 o 3 ·nH 2 Preparation method of O(0