There are not exact figures available on the internet for yout question but still you can have a look at the PSU's who recruites Chemical Engg. Students through GATE

Following are the list of core companies which recruit chemical engineers through either GATE or their own exam each year . One can check their recruitment dates regularly , method of selection procedures and can prepare accordingly .

1. NFL ( National Fertilizers Limited ) 
2. BNPM ( Bank Note Paper Mill )
3. IOCL ( Indian Oil Corporation Limited )
4. HPCL ( Hindustan Petroleum Corporation Limited )
5. BPCL ( Bharat Petroleum Cororation Limited )
6. ONGC ( Oil and Natural Gas Corporation )
7. GAIL ( Gas Authority of India Limited )
8. NALCO ( National Aluminium Corporation Limited )
9. BARC ( Bhabha Atomic Research Centre )
10. DRDO ( Defence Research and Development Organisation )
11. KRIBHCO ( Krishak Bharati Cooperative Limited )