CO2 capture from CO2/N2 mixed gas using synthesized binder-free zeolite X pellets by adsorption technology

Compared with traditional commercial adsorbent zeolite pellets, binder-free molecular sieves can provide better adsorption performance. In this paper, we reported a novel method to synthesize binder-free zeolite X pellets (BF-Z), that is, zeolite X powder was intricately combined with halloysite nanotubes (HNTs) using hydroxypropyl methylcellulose (HPMC), and then the sample was calcinated to form crystals, where HPMC was decomposed and HNTs was also completely converted into binder-free X zeolite. The synthesized BF-Z showed the highest CO 2 adsorption capacity of 4.98 mmol/g at 303 K and 1 bar, compared with commercial NaX zeolites produced by Jianlong, Sigma and UOP companies. Calculated by IAST model, the separation coefficient of CO 2 to N 2 (CO 2 /N 2  = 25/75) on BF-Z is 74 at 303 K and 1 bar. The great separation performance of CO 2 from N 2 (CO 2 /N 2  = 25/75) was also exhibited in breakthrough experiments and a designed VSA process. Compared with commercial NaX (UOP), in breakthrough experiment, BF-Z presented high CO 2 adsorption capacity and rapid adsorption rate; and in designed thirty six-step vacuum swing adsorption process (VSA), the six-bed VSA system using BF-Z as adsorbents demonstrated excellent separation performance such as high CO 2 purity and recovery, low energy consumption and enhanced CO 2 production capacity. The notable efficacy of BF-Z in CO 2 adsorption and separation underscores its promising utility in both commercial and industrial settings.