NOVELTY - An active mixture comprises (pts.mass) industrial anhydrous magnesium chloride powder (48-92), silica sol (1-15), carbon fibers (2-8), deionized water (3-17) and industrial alcohol (2-15) which are mixed with each other.    USE - Active mixture for storing ammonia (claimed) used in car industry.    ADVANTAGE - The solid block is rich in ammonia transporting pore canals, is macroscopically provided with macropores, can fast fill the ammonia and store the ammonia in a better manner, can fast release the ammonia, can be recycled without being crushed, is high in adsorption property and desorption property and is suitable for adsorbing and storing the ammonia. The mixture is suitable for selective catalytic reduction and fuel cell electric vehicle system, and can satisfy the use requirement of the car industry in the future.    DETAILED DESCRIPTION - AN INDEPENDENT CLAIM is included for preparation of active mixture comprising:    (A) doping appropriate amount of silica sol, carbon fibers, deionized water and industrial alcohol into industrial anhydrous magnesium chloride powder, mechanically stirring to obtain a uniformly mixed wet material, then filling the material in a tank body, where the added amount is not greater than 80% of the volume of the tank body; then mechanically oscillating the tank body for 5-10 minutes for eliminating the air gaps;    (B) placing the whole tank body into a vacuum oven, slowly heating the tank body at normal pressure, controlling the temperature at 65-160 degrees C, eliminating the water and ethanol until reaching the constant weight of the mixture, vacuumizing the oven in a stepped manner until reaching 550 mbar, then keeping at constant temperature and constant pressure for 0.5-3 hours, taking out the tank body, and sealing the feed port for preparing an integrated porous solid block of the active mixture for storing ammonia; and    (C) filling the ammonia into the tank body at pressure of 0.05-0.8 MPa until that the absorption of the mixture on the ammonia is saturated.