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Separation of aromatic/alkane mixtures of similar size and properties is critical for the chemical industry as conventional thermal separation is a high-cost and an energy-intensive process. Adsorptive separation based on porous materials is a prospective and economical technology as well as a suitable alternative to the energy-inefficient heat-driven separation process. With this in mind, we design and synthesize a novel microporous polymer (termed CMP-S-1) with a conjugated aromatic skeleton as a porous adsorbent for aromatic/alkane separation. CMP-S-1 possesses high aromatic adsorption selectivity in two representative separation systems (benzene vs cyclohexane and 3-methylthiophene vs n-octane) based on a vapor adsorption experiment and an ideal adsorbed solution theory simulation. The instant adsorption rate, adsorption energy calculations, and liquid fixed-bed breakthrough experiments give convincing demonstrations on the preferential selective adsorption of aromatic compounds over alkanes in CMP-S-1. The strong π–π interaction between aromatics and the naphthalene ring is considered as the main reason for the strong affinity of aromatic compounds in the CMP-S-1 skeleton. The remarkable aromatic/alkane separation performance of CMP-S-1 verifies the important influence of the π-conjugation interaction in the conjugated porous polymer for the low-energy consumption adsorption separation process.

We synthesized three conjugated polycarbazole porous organic frameworks named o-Cz-POF, m-Cz-POF, and p-Cz-POF for hydrocarbon fuels’ adsorptive desulfurization. The carbazole building blocks possessed ortho, meta, and para steric configuration, which resulted in POFs exhibiting adjustable specific surface area and pore structure. Adsorption kinetics experiments and DFT calculations were carried out to understand the competitive adsorption of 3-methylthiophene and octane in the Cz-POF. The instantaneous adsorption rate and adsorption energy calculation analyses gave a convincing demonstration on preferential selective adsorption of 3-methylthiophene in Cz-POFs. Furthermore, the fixed bed breakthrough experiment demonstrated that the Cz-POFs can selectively adsorb 3-methylthiophene efficiently, and hydrocarbon fuel with sulfide content close to 0 ppm was obtained. The features of high stability and high desulfurization efficiency of Cz-POFs make them hold the promise as a new type of porous adsorbent for ultradeep adsorption desulfurization.