Conversion of Dimethyl Ether to a Triptane-Enriched Mixture of Liquid Hydrocarbons: Influence of Modifier and Reaction Conditions

Conversion of Dimethyl Ether to Triptane-Rich Liquid Hydrocarbons on Pd-LaHY with a Hierarchical Porous Structure

“…In choosing hierarchical zeolites (HY h ) to obtain a mixture of liquid hydrocarbons enriched with triptane, we were guided by the results of our previous studies. Earlier, we showed that triptane is formed more selectively from DME on wide-pore FAU-zeolite at a short contact time. ,, This approach creates favorable conditions for the formation of triptane: faster methylation of lower olefins, the primary products of the conversion of dimethyl ether, compared with hydrogen transfer, which terminates the chain with the production of lower alkanes. Zeolites with a hierarchical system are characterized by a developed system of meso- and macropores, which ensures efficient transport of reactant molecules (monomers and oligomers) to catalytically active sites and reverses the unhindered diffusion of reaction products.…”

“…To demonstrate the advantages of HY zeolite with a hierarchical pore system in obtaining a triptane-enriched hydrocarbon mixture from DME, we compared the activity of catalysts with the same composition (0.2Pd- ∼ 0.8LaHY h /30Al 2 O 3 ) based on HY h with a micro-meso-macropore system and traditional microporous HY in this reaction under the same conditions (10 MPa, 340 °C, WHSV DME = 4 h –1 ) (Figure ). For comparison, we used the Pd-1LaHY h /Al 2 O 3 catalyst (according to chemical analysis contains 0.2 wt % PdO, 0.77 wt % La 2 O 3 ), studied in this work, and the Pd-0.75LaHY/Al 2 O 3 catalyst (according to chemical analysis contains 0.2 wt % PdO, 0.75 wt % La 2 O 3 ). As can be seen, the Pd-1LaHY h /Al 2 O 3 sample demonstrated a higher DME conversion and C 5+ selectivity, a higher content of isoalkanes (including triptane) in the product, and half the MeOH content in the condensate.…”

“…The transition to the combined catalyst 1Mg-ZSM-5/0.2Pd-1.1LaHY with a weight ratio of 1:1 led to an increase in the selectivity for liquid hydrocarbons to 88.5 wt % and a decrease in the concentration of MeOH in the aqueous phase of the condensate to 19 wt % and methane in the off gas to 5 wt %. However, the content of triptane in liquid hydrocarbons decreased by more than 2 times …”

“…We have previously shown that a liquid synthetic product with a content of 2,2,3-trimethylbutane of more than 13 wt % can be obtained on a 0.2Pd-1.1LaHY catalyst with a DME conversion of 94% and a liquid HCs selectivity of 83 wt % . However, in the aqueous phase of the condensate, the MeOH content reached ∼40 wt %, and in the off-gas, the methane content exceeded 20 wt %.…”