Hey mahesh!

Both of these branch are good.It is dependent upon you if u wanna work in petroleum industry then petrochemical engineering is the beat branch and in this new era there is an new demand of petrochemical engineering. The chances of getting a good job is there in petrochemical engineering evwn though in chemical engineering.

But if you wanna  study more about chemical other than petroleum then u should take chemical engineering as the option.

Moreover, as petrochemical is an sub branch of chemical engineering . Petrochemical engineering deals with wider scope the new petroleum project coming in future. And the chemical engineering give you more details wider scope.so accordingly there is no downside if u choose and study chemical engineering.

Best of luck!