對二甲苯(p-Xylene)為對苯二甲酸(Terephthalic Acid，簡稱TPA)之原料，而對苯二甲酸主要用途為聚對苯二甲酸二乙酯(PET)之合成。由於PET結構中含苯環，微生物無法分解其結構，若能將p-Xylene中之苯環完全氫化，再將其甲基氧化為羧基，以此化合物與乙二醇進行聚合即可得結構同PET但不含苯環之生物可分解聚合物。為達成此目的， p-Xylene氫化反應速率之提升即成為一重要課題。
在氫化反應過程中，由於氫氣在有機溶劑中之溶解度不高，氣液間會存在著相當大之界面質傳阻力，此外在液體內部的擴散阻力也會對反應速率造成限制。在文獻中已證實，若在液相中加入高壓二氧化碳，可使溶液膨脹而形成二氧化碳膨脹液體(CO2-Expanded Liquid)，增加反應物氣體如氫氣或氧氣於液體中之溶解度，並降低溶液之黏度，對物質在觸媒內部或液相中之質傳速率有所助益，進而增加反應速率。

Dioxide Using a Heterogeneous Rhodium Catalyst. 3. Evaluation of Solvent Effect”, Green Chem., 2002, 4, 507-512.

Inoue, Y., Herrmann, J. M., Schmidt, H., Butt, J. B., Cohen, J. B., “Pt/SiO2 IV. Isotopic Exchange Between Cyclopentane and Deuterium”, J. Catal., 1978, 53, 401-413.

Juszczyk, W., Karpinski, Z., Ratajczykowa, I., Stanasiuk, Z., Zielinski, J., Sheu, L. L., Sachtler, W. M. H., “Characterization of Supported Palladium Catalysts .3. Pd/Al2O3”, J. Catal., 1989, 120, 68-77.

Jin, H. and Subramaniam, B. “Homogeneous Catalytic Hydroformylation of 1-Octene in CO2-expanded Solvent Media”, Chem. Eng. Sci., 2004, 59, 4887-4893.

Keane, M. A., “The Hydrogenation of o-, m-, and p-Xylene Over Ni/SiO2”, J. Catal., 1997, 166, 347-355.

Matsuyama, K., Zhang, D., Urabe T., Mishima, K., “Formation of L-poly(lactic acid) Microspheres by Rapid Expansion of CO2 Saturated Polymer Suspensions”, J. Supercri. Fluids., 2005, 33, 275-281.

Mitsui, S., Imaizumi, S., Nanbu, A., Senda, Y., “Stereochemistry and mechanism of the catalytic hydrogenation of dimethylcyclohexenes”, J. Catal., 1975, 36, 333-337.

Musie, G., Wei, M., Subramaniam, B., Busch, D. H., “Catalytic Oxidations in Carbon Dioxide-Baseed Reaction Media, Including Novel CO2-Expanded Phases”, Coord. Chem. Rev., 2001, 219, 789-820.