The Preparation of Nanosized Pd/ZSM-23 Bifunctional Catalysts for n-Hexadecane Hydroisomerization by Employing PHMB as the Growth Modifier

Abstract

The development of highly effective metal–zeolite bifunctional catalysts for the hydroisomerization of n-alkanes is a paramount strategy to produce second-generation biofuels with high quality. In this study, polyhexamethylene biguanide hydrochloride (PHMB) is precisely added to the initial gel to synthesize nanosized ZSM-23 zeolites (Z23-xPH). Due to orientation adsorption and steric hindrance effects of PHMB, each sample of Z23-xPH demonstrates enhanced mesoporosity in comparison with the conventional Z23-C zeolite. Furthermore, the Brønsted acid density of the Z23-xPH samples is also significantly reduced due to a reduction in the distribution of framework Al at T2–T5 sites. The corresponding Pd/23-C and Pd/Z23-xPH bifunctional catalysts with 0.5 wt% Pd loading for n-hexadecane hydroisomerization are prepared by incorporating ZSM-23 zeolites as acid supports. According to the catalytic test results, the suitable addition of PHMB can effectively promote the iso-hexadecane yield. The Pd/Z23-2PH catalyst with an n _PHMB/n _Si molar ratio of 0.002 demonstrates the highest maximum iso-hexadecane yield of 74.1% at an n-hexadecane conversion of 88.3%. Therefore, the employment of PHMB has provided a simple route for the development of highly effective Pd/ZSM-23 catalysts for n-alkane hydroisomerization.

Keywords

n-Hexadecane hydroisomerization / Nanosized ZSM-23 zeolite / PHMB / Bifunctional catalyst

References

[1] Fan L, Lyu YC, Fu JY, et al. Metal particle size effects over the Ni/SAPO-11 bifunctional catalyst. Appl Surf Sci, 2023, 636.

[2] Ding SZ, Parlett CMA, Fan XL Recent developments in multifunctional catalysts for fatty acid hydrodeoxygenation as a route towards biofuels. Mol Catal, 2022, 523.

[3] Suvarna M, Araújo TP, Pérez-Ramírez J A generalized machine learning framework to predict the space-time yield of methanol from thermocatalytic CO₂ hydrogenation. Appl Catal B, 2022, 315.

[4] Lyu YC, Yu ZM, Yang Y, et al. Metal and acid sites instantaneously prepared over Ni/SAPO-11 bifunctional catalyst. J Catal, 2019, 374: 208-216.

[5] Liu LL, Zhang MW, Wang L, et al. Construction of ordered mesopores outside MTT zeolite for efficient hydroisomerization. Appl Catal A, 2020, 602.

[6] Wang XY, Jia TH, Pan L, et al. Review on the relationship between liquid aerospace fuel composition and their physicochemical properties. Trans Tianjin Univ, 2021, 27(2): 87-109.

[7] Bouchy C, Hastoy G, Guillon E, et al. Fischer–Tropsch waxes upgrading via hydrocracking and selective hydroisomerization. Oil Gas Sci Technol Rev IFP, 2009, 64(1): 91-112.

[8] Shumeiko B, Auersvald M, Straka P, et al. Efficient one-stage bio-oil upgrading over sulfided catalysts. ACS Sustainable Chem Eng, 2020, 8(40): 15149-15167.

[9] Galadima A, Muraza O Hydroisomerization of sustainable feedstock in biomass-to-fuel conversion: a critical review. Int J Energy Res, 2015, 39(6): 741-759.

[10] Wang QA, Shan HC, Sim LB, et al. ZSM-22 synthesized using structure-directing agents of different alkyl chain lengths for controlled n-hexadecane hydroisomerizations. Ind Eng Chem Res, 2023, 62(29): 11470-11479.

[11] Jin DL, Ye GH, Zheng JW, et al. Hierarchical silicoaluminophosphate catalysts with enhanced hydroisomerization selectivity by directing the orientated assembly of premanufactured building blocks. ACS Catal, 2017, 7(9): 5887-5902.

[12] Lian SS, Sun KH, Wang QL, et al. Elucidating the roles of acid site on benzene production from methane dehydroaromatization over the supported Mo catalysts. Chem Phys Lett, 2023, 825.

[13] Wang W, Liu CJ, Wu W Bifunctional catalysts for the hydroisomerization of n-alkanes: the effects of metal–acid balance and textural structure. Catal Sci Technol, 2019, 9(16): 4162-4187.

[14] Park KC, Ihm SK Comparison of Pt/zeolite catalysts for n-hexadecane hydroisomerization. Appl Catal A, 2000, 203(2): 201-209.

[15] Zheng YF, Ding HX, Xing EH, et al. Promoting hydroisomerization selectivity using channel axis reduced ZSM-48 fabricated by a combined bead-milling and porogen-assisted recrystallization method. Catal Today, 2022, 405–406: 30-46.

[16] Chen YJ, Li CA, Chen XA, et al. Synthesis and characterization of iron-substituted ZSM-23 zeolite catalysts with highly selective hydroisomerization of n-hexadecane. Ind Eng Chem Res, 2018, 57(41): 13721-13730.

[17] Guo K, Ma AZ, Wang ZJ, et al. Investigation of n-heptane hydroisomerization over alkali-acid-treated hierarchical Pt/ZSM-22 zeolites. New J Chem, 2022, 46(35): 16752-16763.

[18] Liu SY, Luo CL, Deng X, et al. Toward rational design of narrowly-distributed mesopore on ZSM-22 zeolite for enhanced Pt dispersion and n-alkane isomerization performance. Fuel, 2022, 328.

[19] Tian QW, Liu ZH, Zhu YH, et al. Beyond creation of mesoporosity: the advantages of polymer-based dual-function templates for fabricating hierarchical zeolites. Adv Funct Mater, 2016, 26(12): 1881-1891.

[20] He LW, Fu WQ, Li LY, et al. Study of CA-treated ZSM-22 zeolite with enhanced catalytic performance in the hydroisomerization of long-chain n-dodecane. New J Chem, 2021, 45(5): 2820-2829.

[21] Li XY, Sun MH, Rooke JC, et al. Synthesis and applications of hierarchically porous catalysts. Chin J Catal, 2013, 34(1): 22-47.

[22] Liu SY, Ren J, Zhang HK, et al. Synthesis, characterization and isomerization performance of micro/mesoporous materials based on H-ZSM-22 zeolite. J Catal, 2016, 335: 11-23.

[23] Wang ZY, Wang YQ, Sun C, et al. Seed-assisted synthesis and catalytic performance of nano-sized ZSM-5 aggregates in a one-step crystallization process. Trans Tianjin Univ, 2020, 26(4): 292-304.

[24] Han L, Cui X, Liu X Particle size control for SAPO-11 molecular sieves. Chinese Inorg Chem, 2013, 29(3): 565-570.

[25] Chen LH, Sun MH, Wang Z, et al. Hierarchically structured zeolites: from design to application. Chem Rev, 2020, 120(20): 11194-11294.

[26] Liu Y, Qu W, Chang WW, et al. Catalytically active and hierarchically porous SAPO-11 zeolite synthesized in the presence of polyhexamethylene biguanidine. J Colloid Interface Sci, 2014, 418: 193-199.

[27] Zhang F, Liu Y, Sun Q, et al. Design and preparation of efficient hydroisomerization catalysts by the formation of stable SAPO-11 molecular sieve nanosheets with 10–20 nm thickness and partially blocked acidic sites. Chem Commun, 2017, 53(36): 4942-4945.

[28] Shang ZY, Chen Y, Zhang LJ, et al. Plate-like MFI crystal growth achieved by guanidine compounds. Inorg Chem Front, 2022, 9(9): 2097-2103.

[29] Su XF, Liu BY, Feng CQ, et al. Rapid and low-cost synthesis of ZSM-5 zeolite nanosheet assemblies for conversion of methanol to gasoline. Microporous Mesoporous Mater, 2022, 344.

[30] Rima D, Djamal D, Fatiha D Synthesis of high silica zeolites using a combination of pyrrolidine and tetramethylammonium as template. Mater Res Express, 2018, 6(3

[31] Feng CQ, Su XF, Wang W, et al. Facile synthesis of ultrafine nanosized ZSM-5 zeolite using a hydroxyl radical initiator for enhanced catalytic performance in the MTG reaction. Microporous Mesoporous Mater, 2021, 312.

[32] Lippmaa E, Maegi M, Samoson A, et al. Investigation of the structure of zeolites by solid-state high-resolution silicon-29 NMR spectroscopy. J Am Chem Soc, 1981, 103(17): 4992-4996.

[33] Chen ZQ, Liu SY, Wang HH, et al. Synthesis and characterization of bundle-shaped ZSM-22 zeolite via the oriented fusion of nanorods and its enhanced isomerization performance. J Catal, 2018, 361: 177-185.

[34] Holzinger J, Nielsen M, Beato P, et al. Identification of distinct framework aluminum sites in zeolite ZSM-23: a combined computational and experimental ²⁷Al NMR study. J Phys Chem C, 2019, 123(13): 7831-7844.

[35] Liu R, Zhang JE, Sun XL, et al. An oniom study of the distribution of skeletal Al atoms and Brønsted acidity in ZSM-23 zeolite. J Theor Comput Chem, 2014, 13(7): 1450059.

[36] Sun JZ, Xiong SX, Lin HL, et al. The effects of growth modifiers on the catalytic performance of hierarchical Pd/ZSM-23 bifunctional catalysts for n-hexadecane hydroisomerization. Fuel, 2023, 347.

[37] Zhang MW, Liu LL, Wang L, et al. Four-carbon segmented discrete hydrocracking of long-chain paraffins in MTT channels following a pore-mouth mechanism. ACS Catal, 2022, 12(16): 10313-10325.