The distillation method for extracting anhydrous ethanol from the volatile benzene water requires continuous supervision in the petro-chemical industry. This paper describes the design process and numerical analyses of a PCF sensor with a hollow core for sensing the petro-chemical constituents, namely ethanol, water, and benzene, in the 2 THz range. Photonic crystal fiber sensors have many possible applications in the petro-chemical industry, environmental monitoring, biomedicine, and food preservation. An optical fiber-based sensor with simultaneous low loss and enhanced sensitivity is intended to detect this petro-chemical effectively and safely. The Finite Element Method (FEM) framework is used to quantify the exhibition of the suggested fiber sensor. The simulation outcomes on the suggested sensor model demonstrate very satisfactory results on the relative sensitivity as 99.55 $\%$, 99.44 $\%$ and 99.59 $\%$ confinement loss as $2\times 10-17$ dB/cm, $1\times 10-16$ dB/cm and $1.17\times 10-16$ dB/cm, Effective Material Loss (EML) as 0.00043 cm$-1$, 0.00054 cm$-1$ and 0.00038 cm$-1$ for Ethanol, Water and Benzene, respectively and the Effective areas (EAs) are $2.85\times 10-7$ $𝑚2$ for Ethanol, $2.91\times 10-7$ $𝑚2$ for Water and $2.82\times 10-7$ $𝑚2$ for Benzene at 2 THz frequency regime.