Controllable wettability on Ni foam with PDA coatings and gas–liquid mass transfer enhancement in micropacked bed reactors

[Display omitted] •Hydrophilic and hydrophobic modified Ni foam packings are prepared by coating PDA.•The WCA of the modified Ni foam packing is controlled in the range of 0–151.5°.•Modified Ni foam packings have excellent mechanical and chemical stability.•A 35.6–160.2% enhancement ratio of kLa is obtained in μPBRs.•Models of kLa and f with WCAs are established. A micro-nano coating with controllable wettability is constructed on Ni foam using the dipping coating method, incorporating organic polydopamine (PDA) and 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and inorganic SiO2 nanoparticles. PDA has the properties of controlling wettability, strong adhesion, and abundant grafting sites. The water contact angle (WCA) of modified Ni foam is controlled in the range of 0–151.5°. The stability measurement displays that modified Ni foam packings exhibit excellent acid and alkali resistance as well as mechanical stability to fluid erosion under microenvironment. Compared with non-modified (131.5°) and superhydrophilic (0°) Ni foam packings, the maximum ratios of mass transfer enhancement for the superhydrophobic (151.5°) Ni foam packing are 35.6 % and 160.2 %, respectively. Empirical correlations of the gas–liquid mass transfer coefficient and friction factor are established considering the effect of the WCA, and errors between predicted values and experimental values are within ± 15 % and ± 10 %, respectively.