The present disclosure provides means to produce glycolaldehyde dialkyl acetal in high yield. One aspect of the present disclosure relates to a method for producing glycolaldehyde dialkyl acetal including a glycolaldehyde formation step of converting paraformaldehyde to glycolaldehyde in an ether type solvent in a presence of an N-heterocyclic carbene catalyst, and an acetalization step of treating the glycolaldehyde with an alcohol solution of hydrogen chloride to obtain the glycolaldehyde dialkyl acetal. The N-heterocyclic carbene catalyst is a compound represented by a formula (I) or (II) [in the formulae, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, and R.sup.8, and A.sup. have meanings described in description and the appended claims], and the glycolaldehyde formation step and the acetalization step are performed in a single container.

##STR00001##

A regeneration method of a nitrogen-containing carbon catalyst includes the following steps: roasting the nitrogen-containing carbon catalyst in a nitrogen-containing atmosphere to obtain a regenerated nitrogen-containing carbon catalyst. The method is a universal method, which is suitable for nitrogen-doped carbon catalysts and can be used to regenerate a nitrogen-containing carbon catalyst for producing vinyl chloride (VC) through 1,2-dichloroethane cracking. The method can greatly reduce the production cost of the catalyst and increase the service life of the catalyst, and a regeneration process thereof is fast, simple, and controllable, and does not require high temperatures.