The invention provides a preparation method of high purity
phosphorus pentafluoride. The preparation method comprises the following steps: step one, taking polyphosphoric acid and waterless
hydrogen fluoride as the primary raw materials to prepare a
hexafluorophosphoric acid water solution; step two, reacting the
hexafluorophosphoric acid water solution obtained in the step one with
sulfur trioxide so as to obtain a mixture of
hexafluorophosphoric acid and
sulfuric acid; step three, directly heating the mixture of the hexafluorophosphoric acid and
sulfuric acid obtained in the step two without separation, condensing the generated
phosphorus pentafluoride steam so as to obtain a coarse product of
phosphorus pentafluoride; step four, refining the obtained coarse product so as to obtain high purity
phosphorus pentafluoride with a purity more than 99.5%. The product prepared by the provided preparation method has a high purity and low purity content, wherein the
phosphorus pentafluoride content is not less than 99.95%, the waterless
hydrogen fluoride content is not more than 50 ppm, the
water content is not more than 10 ppm, the
metal ion content is not more than 1 ppm, and the content of other purities is not more than 5 ppm.