Method for preparing 5A molecular sieve for straight-chain paraffin adsorption through adopting attapulgite

Abstract

The invention relates to a method for preparing a 5A molecular sieve for straight-chain paraffin adsorption through adopting attapulgite, and belongs to the technical field of molecular sieve adsorbents. The method comprises the following steps: 1, calcining attapulgite at a high temperature, and immersing in a hydrochloric acid solution; 2, fully dissolving attapulgite in an aqueous solution of sodium hydroxide; 3, fully dissolving sodium hydroxide and sodium metaaluminate in water; 4, rapidly mixing a solution obtained in step 2 with a solution obtained in step 3, violently stirring to obtain a milky colloid, crystallizing the colloid at 80-95DEG C for 4-6h, cooling, filtering, washing until the pH value is less than 9, and drying to obtain raw powder of a 4A molecular sieve; and 5, carrying out ion exchange of the raw powder of a 4A molecular sieve and a calcium chloride solution to obtain the 5A molecular sieve. The static saturated adsorption capacities of the 5A molecular sieve to n-decane and n-pentadecane reach 0.0716g / g and 0.123g / g respectively. The method for preparing the 5A molecular sieve through adopting a cheap and easily available attapulgite resource is used to substitute a traditional chemical raw material method, and the 5A molecular sieve has a good saturated adsorption capability to straight-chain paraffin.

Description

technical field [0001] The invention relates to a method for preparing 5A molecular sieve by using attapulgite clay. The molecular sieve is suitable for linear alkanes (n-decane n -C 10 ~ Pentadecane n -C 15 ) has better adsorption selectivity and equilibrium adsorption capacity, and belongs to the technical field of molecular sieve adsorbents. Background technique [0002] Selective adsorption of liquid wax (n-alkanes C) from straight-run kerosene 10 -C 15 ) molecular sieve dewaxing technology, mainly using 5A molecular sieve adsorbent. The actual effective pore diameter of 5A molecular sieve is 0.51nm, the maximum critical diameter of n-alkane molecules is about 0.49nm, the minimum diameter of isoparaffins, naphthenes and aromatic hydrocarbons is above 0.55nm, and the effective pore diameter of 5A molecular sieve is in the range of n-alkane Between the critical diameter of molecules and non-n-alkane molecules, 5A molecular sieve can selectively adsorb n-alkane, so as...

AI Technical Summary

Problems solved by technology

[0003] Attapulgite clay is rich in reserves in my country. It is a cheap silicon-containing inorganic mineral and an ideal raw material for the synthesis of A-type molecular sieves. There is no domestic research on the application of 5A molecular sieves prepared from attapulgite to the adsorption of heavy liquid wax. This case The inventor proposed a method for synthesizing 5A molecular sieve from modified attapulgite and applying it to the adsorption and separation of linear alkanes