Abstract: The present disclosure provides a preparation method of a titanium implant with a surface coating in a crater-like porous shape. A titanium substrate is subjected to polishing, cleaning, and first drying in sequence to obtain a pretreated titanium substrate. This step eliminates an influence of roughness and surface impurities of the titanium substrate on roughness and a structure of a coating formed on a surface of the titanium substrate after micro-arc oxidation, so as to obtain a titanium implant with a specific structure and a desirable biological performance. The micro-arc oxidation is conducted using the pretreated titanium substrate as an anode and iron as a cathode in an electrolyte containing sodium phosphate. In this step, a micro-arc oxidation coating is formed on the surface of the titanium substrate to obtain the titanium implant with a surface coating in a crater-like porous shape.

Abstract: A guard catalyst, comprising an alumina support and molybdenum and/or tungsten and nickel and/or cobalt supported on the alumina support, wherein the total ammonia integral adsorption heat of said alumina support does not exceed 25 J/g, the percentage taken up by the ammonia integral adsorption heat of the ammonia differential adsorption heat greater than 100 kJ/mol does not exceed 10% of the total ammonia integral adsorption heat. Compared to the catalysts of the prior art, the guard catalyst has higher catalytic activity, less coke deposit, lower reduction rate of pore volume, better stability of activity, and higher strength.

Abstract: A guard catalyst, comprising an alumina support and molybdenum and/or tungsten and nickel and/or cobalt supported on the alumina support, wherein the total ammonia integral adsorption heat of said alumina support does not exceed 25 J/g, the percentage taken up by the ammonia integral adsorption heat of the ammonia differential adsorption heat greater than 100 kJ/mol does not exceed 10% of the total ammonia integral adsorption heat. Compared to the catalysts of the prior art, the guard catalyst has higher catalytic activity, less coke deposit, lower reduction rate of pore volume, better stability of activity, and higher strength.