My undergraduate GPS was ~2.7. So I did a MS at a lower ranked school, still got paid and then used that experience to get into a world class PhD program.
And any amount of research will increase your chance.
Even if you can not get paid to get the MS, at least try and get the tuition provided (graduate tuition is usually 3X higher then undergraduate). You usually teach undergraduate labs, so its not free, its a job with tuition comped.
Also, you are not limited to going into a MS for Chemical Engineering. You could just as well get into just a Chemistry MS program (more options available for that) and then do PhD in Chemical Engineering no problem. When you then go into a PhD program in Chemical Engineering, yes, you will be a little behind and will need to work your but off at first to catch up. And during the MS program if it is not Chem Eng maybe some of your elective classes can be those classes that you need for Chem Eng.
Conversely, depending on what is available at the school you chose; you can get a MS in Chemistry and a BS in Chemical Engineering at the same time (all for free/being paid hopefully), since you said you have 2 years of BS Chem Eng classes, and it is 2 years for MS. You will be working really hard.
Yes, if it is the only option, going back and spending 2 years getting the degree you want to get the career you want, it is worth it. But I would really try hard to find a paid MS program first, even if it has to be in Chemistry.
If you go back and spend 2 years getting the degree, with the price of tuition, student loan cost, current student loan inflation rate (crazy high) and percentage interest rate, and then factoring in the amount of time lost getting to the job market; you will have made nearly $400,000 (US) less then if you can get into a graduate program right now over the next 20 years. The difference is owning your own house in 20 years vs still paying off the mortgage.