TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Apparatus: The reactor is two-section insulating reactor in which the entrance temperature of first section is 25-85 degrees C and Hhydrogen/acetylene volume ratio is 1-3:1, and the entrance temperature of second section is 30-90 degrees C and hydrogen/acetylene volume ratio is 1.5-4:1, or the reactor is a three-section insulating reactor in which the entrance temperature of first section is 30-65 degrees C and hydrogen/acetylene volume ratio is 0.6-1.5:1, entrance temperature of second section is 40-70 degrees C and hydrogen/acetylene volume ratio is 1-3:1, and entrance temperature of a third section is 50-85 degrees C and hydrogen/acetylene volume ratio is 1.5-4:1.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The catalyst contains 0.03-0.05 %mass of palladium. The dispersion of palladium and silver is 35-65 %mass. Preferred Properties: The catalyst has specific surface area of 10-100 m2/g, pore volume of 0.2-0.6 ml/g and bulk density of 0.5-1.0 g/cm3. The alumina carrier is obtained by modifying other elements, e.g. silicon or titanium. The catalyst is obtained by preparing palladium-magnesium-aluminum-carboante-LDH/alumina precursor (A), preparing palladium-magnesium-aluminum-aluminum(complex)-LDHs/alumina (B), preparing palladium-magnesium-aluminum-silver (complex)-LDHs/Al2O3 precursor (C), and calcining the precursors. Palladium salt, magnesium salt and soluble organic amine are dissolved in mixed solution in the volume of 80-120% with respect to the whole volume of the carrier. Alumina is added into the mixed solution to be absorbed by the solution and reacted for 5-24 hours at 80-200 degrees C. The mixture is cooled and solid particles are removed using deionized water, dried at 80-120 degrees C to obtain precursor (A). A coordination compound ion solution of silver is prepared in the volume ratio of 80-120% of the whole volume of the precursor and the pH is adjusted to 3-6. The precursor (A) is added to the prepared solution, and reacted at 80-150 degrees C for 5-24 hours. The reaction solution is cooled and the solid particles are removed using deionized water, dried and calcined to obtain precursor (B). The precursor (B) is calcined to obtain the catalyst. palladium salt is palladium nitrate dehydrate or palladium chloride. The magnesium salt is magnesium nitrate hexahydrate, magnesium chloride hexahydrate or magnesium sulfate heptahydrate. The coordination compound ion of silver is Ag(SCN)2-, Ag(EDTA)3- or Ag(S2SO3)2-asteriskasteriskasteriskasteriskasteriskasteriskasteriskasteriskasteriskasteriskasterisk.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The soluble amine is urea or hexamethylenamine.