Recently, a team led by Prof. Weibin Fan from the Institute of Coal Chemistry (ICC) of the Chinese Academy of Sciences (CAS), has made significant progress in the aromatization of light alkanes. The research results were published in Chinese Journal of Catalysis, titled “Single [Ga(OH)]²⁺ species supported on mesoporous hollow-structured H-ZSM-5: A highly efficient light alkanes aromatization catalyst”.

ABSTRACT: Aromatization of light alkanes is a value-added process in both petrochemical and coal chemical industries. Here, single [Ga(OH)]²⁺ ion-exchanged mesoporous hollow-structured ZSM-5 (Ga-MH-ZSM-5) material was prepared, and it shows unprecedented catalytic performance in light alkane aromatization, with considerably enhanced activity, product selectivity and catalytic stability. The average aromatics yields in ethane aromatization at 600 °C and WHSV of 0.8 h^-1 within 28 h and in propane aromatization at 580 °C and WHSV of 1.1 h^-1 within 20 h reach ~18.4% and ~70.8% with benzene, toluene and xylenes (BTX) accounting for ~96% and ~88% of total aromatics, respectively. Ga-MH-ZSM-5-0.41 gave a TON for formation of aromatics (TON_aromatics) from propane as high as 57479, being much higher than the best-performance reported in literature (≤5514). This also holds true for ethane aromatization; the TON_aromatics obtained on Ga-MH-ZSM-5-0.41 was ≥ 3845, in contrast to ≤ 392 on reported non-noble metal catalysts in literature. The catalytic activity of Ga-MH-ZSM-5 highly depends on Ga species structures. [Ga(OH)]²⁺ ions are predominant species at Ga loading ≤ 0.3 wt%, while more [Ga(OH)₂]⁺ and GaO_x oligomers are formed with increasing Ga content. Upon reduction with H₂, [Ga(OH)]²⁺ and [Ga(OH)₂]⁺ are transformed into [GaH]²⁺ and [GaH₂]⁺ species, which show a propane dehydrogenation rate of 300 and 15 times of that of Brønsted acid sites respectively. The light alkanes are mainly dehydrogenated into light olefins on [GaH]²⁺ species, and then, oligomerized and cyclized into (alkyl)cycloalkanes on H⁺ sites, which is followed by ring expansion on H⁺ and sequential dehydrogenations into aromatics primarily on [GaH]²⁺.

https://doi.org/10.1016/S1872-2067(25)64678-X