I prefer to use a cement based adhesive with porcelain but ardex do a tubbed adhesive which would be fine for small format tiles.....
ARDEX D 30
Size (pack): 10ltr
Coverage: Approximately 1 litre per m² using a 3mm x 3mm toothed and notched trowel.
ARDEX D 30 is a water resistant, non-slip ready mixed wall tile adhesive for use in commercial and domestic showers, kitchens and bathrooms. Suitable for virtually all substrates and tile types, including porcelain, ARDEX D 30 does not need a primer and is easy to use with excellent application properties.
ARDEX D 30 is classified as D2 TE (improved dispersion adhesive with additional characteristics, reduced slip and extended open time) in accordance with BS EN 12004.
or use a cement based one.......
BAL Single Part Flexible
A flexible, non-slip, water-resistant and frost-resistant wall and floor tile adhesive, especially suitable for fixing tiles, including fully vitirfied and porcelain tiles to low porosity backgrounds/bases. Suitable for use on concrete/brick/block walling, cement:sand rendering, plaster, plasterboard, cement sheets, tile backer boards, concrete bases, cement:sand screeds, plywood overlay, ceramic/quarry tile/terrazzo/hard natural stone, vinyl tiles/sheet bases, mastic asphalt. Conforms to BS EN 12004, Type C, Class 2T.
And don't forget to use a flexible grout........
good luck.....
