An ab initio (DFT PW91) periodic model based on silica sodalite is applied to investigate the structure and energetics of formation and interconversion of defect centers in zeolites and related microporous materials. We calculate low energies of formation for a new range of defects including peroxy species which should be important Lewis and redox centers. The formation of such defects is shown to be facilitated by the presence of vicinal disilanols and Bronsted acid sites in these materials.