What is the lower end of the range for 2022 auto production forecasts due to the ongoing microchip shortage and other auto supply chain issues? 
ff to a great start this year. And while it's too early in the year to measure pavement technologies, we believe we'll see good growth as countries globally expand their paving operations.
The outlook for performance materials is less certain. Forecast for 2022 auto production are conservative due to the ongoing microchip shortage and other auto supply chain issues. Q4 2021's chip availability improved from Q3, but we're not confident the sustainable rate of supply has been achieved. For 2022, the lower end of our range assumes continued supply constraints in the first half of the year, followed by some recovery in the second half.
To the extent industry dynamics improve and recover sooner, we would end up at the higher end of our range. We will continue to invest organically as we bring online our new polyol capability in DeRidder and an alternate fatty acid stream in Crossett. Additionally, we are working on several debottlenecking projects at our performance materials facilities. We are also in the execution phase of our SAP S/4HANA implementation.
Capex will be elevated somewhat from recent levels, but we consider these investments well worth the effort as they exceed our investment return expectations and will help us sustain our highly profitable growth. Finally, we will continue to return capital to shareholders as we see opportunities to buy back shares in what we consider attractive levels. I'm confident our team will deliver a strong performance this year. Before we go to Q&A, I would like to take a moment to thank Mike Smith for her service to Ingevity.
This will be his last earnings call. And going forward, you will hear from Rich and Steve. Mike, while we know we will still see you around, we thank you, and we wish you the best of luck. In closing, I appreciate ongoing hard work and efforts of all of our employees worldwide.
We hope you share our enthusiasm for Ingevity. And at this point, we'll take your questions.
Questions & Answers:
Operator
[Operator instructions] The first question today comes from Vincent Anderson of Stifel. Vincent, please go ahead. Your line is open.
Vincent Anderson -- Stifel Financial Corp. -- Analyst
Good morning. Can you hear me, OK?
Mary Hall -- Executive Vice President and Chief Financial Officer
You broke up just a little bit. Go ahead.
Vincent Anderson -- Stifel Financial Corp. -- Analyst
I'll give it a -- I'll give it a shot. Just yell at me if it keeps breaking up. Can you speak to the revenue mix in engineered polymers this quarter between monomer, raw material pass-through, and derivatives and where that could trend over the course of 2022 as it relates kind of to your margin expectations on that business?
Mike Smith -- President of Performance Chemicals
Yeah. Thanks. So in general, our mix for derivatives versus monomers, we expect that to continue to be more toward derivatives. From a volume standpoint, that mix didn't change too much in 2021 as all areas of the engineered polymers business grew quite significantly.
But as we described over time, our focus and working closely with our customers is to continue to drive the derivative sales in both polyols and thermoplastics. And as evidence of that, of course, we're very much looking forward to getting the start-up of our new polyol facility in DeRidder here in the middle of this year.
Vincent Anderson -- Stifel Financial Corp. -- Analyst
OK. Thank you. And can you -- just staying on performance chemicals, could you discuss your CTO costs and importantly your availability heading into 2022 on the portion of your supply that is not covered under long-term agreements?
Mike Smith -- President of Performance Chemicals
Yes. So we had anticipated, and we're seeing raw material cost inflation on CTO. In terms of availability, we anticipate being able to get what we planned for. That's what we entered the year believing in our outlook continues to demonstrate that.
John Fortson -- President and Chief Executive Officer
Put another way, Vincent, I mean, out of, call it, 320,000 tons of stuff that we're using, it's pretty much eve
ff to a great start this year. And while it's too early in the year to measure pavement technologies, we believe we'll see good growth as countries globally expand their paving operations.
The outlook for performance materials is less certain. Forecast for 2022 auto production are conservative due to the ongoing microchip shortage and other auto supply chain issues. Q4 2021's chip availability improved from Q3, but we're not confident the sustainable rate of supply has been achieved. For 2022, the lower end of our range assumes continued supply constraints in the first half of the year, followed by some recovery in the second half.
To the extent industry dynamics improve and recover sooner, we would end up at the higher end of our range. We will continue to invest organically as we bring online our new polyol capability in DeRidder and an alternate fatty acid stream in Crossett. Additionally, we are working on several debottlenecking projects at our performance materials facilities. We are also in the execution phase of our SAP S/4HANA implementation.
Capex will be elevated somewhat from recent levels, but we consider these investments well worth the effort as they exceed our investment return expectations and will help us sustain our highly profitable growth. Finally, we will continue to return capital to shareholders as we see opportunities to buy back shares in what we consider attractive levels. I'm confident our team will deliver a strong performance this year. Before we go to Q&A, I would like to take a moment to thank Mike Smith for her service to Ingevity.
This will be his last earnings call. And going forward, you will hear from Rich and Steve. Mike, while we know we will still see you around, we thank you, and we wish you the best of luck. In closing, I appreciate ongoing hard work and efforts of all of our employees worldwide.
We hope you share our enthusiasm for Ingevity. And at this point, we'll take your questions.
Questions & Answers:
Operator
[Operator instructions] The first question today comes from Vincent Anderson of Stifel. Vincent, please go ahead. Your line is open.
Vincent Anderson -- Stifel Financial Corp. -- Analyst
Good morning. Can you hear me, OK?
Mary Hall -- Executive Vice President and Chief Financial Officer
You broke up just a little bit. Go ahead.
Vincent Anderson -- Stifel Financial Corp. -- Analyst
 I'll give it a -- I'll give it a shot. Just yell at me if it keeps breaking up. Can you speak to the revenue mix in engineered polymers this quarter between monomer, raw material pass-through, and derivatives and where that could trend over the course of 2022 as it relates kind of to your margin expectations on that business?
Mike Smith -- President of Performance Chemicals
Yeah. Thanks. So in general, our mix for derivatives versus monomers, we expect that to continue to be more toward derivatives. From a volume standpoint, that mix didn't change too much in 2021 as all areas of the engineered polymers business grew quite significantly.
But as we described over time, our focus and working closely with our customers is to continue to drive the derivative sales in both polyols and thermoplastics. And as evidence of that, of course, we're very much looking forward to getting the start-up of our new polyol facility in DeRidder here in the middle of this year.
Vincent Anderson -- Stifel Financial Corp. -- Analyst
OK. Thank you. And can you -- just staying on performance chemicals, could you discuss your CTO costs and importantly your availability heading into 2022 on the portion of your supply that is not covered under long-term agreements?
Mike Smith -- President of Performance Chemicals
Yes. So we had anticipated, and we're seeing raw material cost inflation on CTO. In terms of availability, we anticipate being able to get what we planned for. That's what we entered the year believing in our outlook continues to demonstrate that.
John Fortson -- President and Chief Executive Officer
Put another way, Vincent, I mean, out of, call it, 320,000 tons of stuff that we're using, it's pretty much eve