Patent ID: 8318123

Claim:
A method of preparing carbon nanotubes (CNTs) comprising: decomposing a polymer with hydrotalcite as a catalyst, comprising: A. mixing the hydrotalcite with a particle size at nanometer or sub-micron level and the polymer uniformly by a mixing mill or an extruder at 130-250° C., a mass ratio of the hydrotalcite to the polymer being in a range of 1:100-2:1; B. calcining the mixture obtained from step A in a muffle furnace at 200-1500° C. for 1-360 minutes; and C. adding a product obtained from step B into a 1-6 mol/L nitric acid solution at 50-280° C., refluxing for 1-48 hours, and then treating the product by centrifugation, washing, and drying to obtain the CNTs, wherein the formula of the hydrotalcite is: [M 2+ 1−x M 3+ x (OH) 2 ] x+ .(A n− ) x/n .mH 2 O, where the M 2+ is one, two or three types selected from the group consisting of Mg 2+ , Ni 2+ , Cu 2+ , Co 2+ , Fe 2+ , Zn 2+ , Mn 2+ , Cd 2+ , Ca 2+ , Pd 2+ and Pt 2+ , M 3+ is one or two types selected from the group consisting of Al 3+ , Cr 3+ , Co 3+ , Fe 3+ , Ga 3+ , V 3+ and In 3+ , 0.2≦x≦0.33, m is the number of crystal water that has a range of 0.5-9; wherein the hydrotalcite is prepared by a coprecipitation method, a separate nucleation and aging steps method, a non-equilibrium crystallization method or a hydrothermal synthesis method; and wherein the polymer comprises polyethylene, polypropylene, polyisobutylene, polymethylpentene or poly acrylonitrile-butadiene-styrene.