The present invention relates to a Pd- and Au-containing shell catalyst which is characterised by an improved Pd and Au distribution. The invention also relates to two methods for producing said catalyst and to a method for producing vinyl acetate monomer using said catalyst.

Disclosed are (2,2-dimethyl-1,3-dioxolan-4-yl)methyl 2-bromo-2,2-difluoroacetate, a waterborne polyurethane, and preparation methods thereof. The (2,2-dimethyl-1,3-dioxolan-4-yl)methyl 2-bromo-2,2-difluoroacetate could be used as a modified monomer for preparing a waterborne polyurethane, and substituents at a C2 position of the (2,2-dimethyl-1,3-dioxolan-4-yl)methyl 2-bromo-2,2-difluoroacetate are two fluorine atoms and one bromine atom. When it is used for preparing the waterborne polyurethane, fluorine and bromine groups are introduced into the structure of the waterborne polyurethane, and the resultant waterborne polyurethane exhibits good moisture resistance and flame retardance.