Porous liquids are fluids with the permanent porosity, which can overcome the poor gas solubility limitations of conventional porous solid materials for three phase gas-liquid-solid reactions. However, preparation of porous liquids still requires the complicated and tedious use of porous hosts and bulky liquids. Herein, we develop a facile method to produce a porous metal-organic cage (MOC) liquid (Im-PL-Cage) by self-assembly of long polyethylene glycol (PEG)-imidazolium chain functional linkers, calixarene molecules and Zn ions. The Im-PL-Cage in neat liquid has permanent porosity and fluidity, endowing it with a high capacity of CO2adsorption. Thus, the CO2stored in an Im-PL-Cage can be efficiently converted to the value-added formylation product in the atmosphere, which far exceeds the porous MOC solid and nonporous PEG-imidazolium counterparts. This work offers a new method to prepare neat porous liquids for catalytic transformation of adsorbed gas molecules.