Supremacy of in-situ doping over surface loading technique for the preparation of alkali metal-promoted tellurates as efficient reusable catalysts to approach hydroxylation and dehalogenation of aryl halides

[Display omitted] •Supremacy of in situ doping over surface loading technique.•Alkali-metal promoter for the hydroxylation and dehalogenation of aryl halides.•Decreasing order of activity is K-Cu3TeO6 > Na-Cu3TeO6 > Rb-Cu3TeO6 > Cs-Cu3TeO6.•Flame photometry and XPS reveals the presence “K” in the fresh and reused catalyst. The novel alkali metal doped transition metal tellurate catalysts are prepared by two different methods, namely the in-situ doping method (alkali metal is added to the hydroxides of copper and tellurium and then calcinated) and surface loading method (alkali metal is added to the as-prepared metal tellurate and then calcined second time). In this study, the supremacy of in-situ doping over surface loading of alkali metal promoters (AM: Na, K, Rb, or Cs) to the metal tellurate for hydroxylation of aryl halides and dehalogenation of aryl halides reactions are investigated. Besides, the catalytic activity depends on the AM used for doping; the decreasing order of activity is K-Cu3TeO6 > Na-Cu3TeO6 > Rb-Cu3TeO6 > Cs-Cu3TeO6 and the occupancy of AM is in the sequence of Cs+