how can I start a zero budget business after chemical engineering?

Hello.

If you have almost no money then it is the biggest disadvantage you have. Any kind of business be it a small scale or a large one needs capital.

So I'd suggest that first you get a job and do some savings or else you'll have to take help from a bank, but taking a loan from a bank can involve many risks.

Still I'll put up some points where I think you can setup your own venture.

1. Column internals:

Many large and small scale chemical plants needs internals for their distillation columns, extractors, srubbers, these internals can be different kind of packings, distributors, trays, mesh, packing support etc.

2. Water treating chemicals:

The cooling water, chilled water, brine, boiler feed, and water used for other applications in a chemical plant needs periodic treatment as the same water is being recycled and reused to minimize the consumption, speciality chemicals are added to reduce the fouling tendency of water and to avoid scale formation in the equipments to increase their life.

3. Primary raw materials:

There are many substances , compounds, mixtures that are used on a large scale as raw materials and intermediates, Primary because they are easy to produce and don't involve complex mechanisms and procedures. Some common examples are caustic, HCl, methanol, etc.

I'll add some more later, but keep one thing in mind the most important thing is customers and clients, until and unless you have a strong customer base producing anything is of no use, marketing your products in the right way and giving the best deals compare to your competitors is the key to success.

Hope this helps.