**1. Introduction**

para-Xylene (pX) is a key raw material in the production polyethylene terephthalate (PTA) before it is combined with mono ethylene glycol (MEG) to produce polyethylene terephthalate (PET), one of the largest and fastest globally growing polymers. Demand for pX is driven by the global polyester growth. Global polyester consumption is currently around 80 million tonnes/year. Using application of PET in fiber, this polyester is produced in 57.7 million metric tonne in 2019. Since 2008, the average growth in production has an annual increase of 5.9% (see **Figure 1**) [1]. Industry forecasts are that polyester will continue to grow at approximately 4% annually. While there is also increased focus on recycling polyester (a.k.a. rPET), most industry experts also see continued demand growth in virgin material due to limits on the availability of recycled polyester and need for virgin material to meet quality and specifications of many applications. Over the span between 2008 and 2019, rPET produced has ranged from 2 to 9% of total global PET for fiber applications. Currently, PTA is produced from pX where 0.58 tonnes of pX are required to produce one tonne of polyester, resulting in global demand for pX of about 50 mm tonnes (**Figure 2**).

**Figure 3** displays the supply chain to produce PET. Virtually all PET is produced from fossil fuel resources. pX is produced from mixed xylenes that are derived from crude oil, and MEG is produced from ethylene primarily derived from natural gas. There is a commercial bio-based route to MEG that starts from ethanol produced

### **Figure 1.** *Annual PET Fiber produced from 2008 to 2019.*

**Figure 2.**

*Pathway from p-xylene to polyethylene terephthalate (PET).*

from biomass by dehydration to ethylene, oxygenation to ethylene oxide, and hydrolysis to MEG. Bio-based MEG is used to produce a partial bio (~30%) PET. At the current time, there are no commercial routes to bio-pX.

### *Catalytic Fast Pyrolysis of Lignocellulosic Biomass to Benzene, Toluene, and Xylenes DOI: http://dx.doi.org/10.5772/intechopen.99946*

Conventional pX technology is based on the isomerization of mixed xylenes which has been practiced commercially for decades. The mixed xylenes are produced by catalytic reforming of naphtha, which produces a C8 stream that includes the three xylene isomers and ethylbenzene. Other routes to mixed xylenes are from the pyrolysis gasoline stream produced in a naphtha steam cracker. The main commercial routes used to separate the pX isomer are crystallization, which takes advantage of the different freeze points of the ortho-, meta- and para- isomers, or via selective adsorption separation processes.

As a result of growing concerns about climate change, companies, governments, and consumers are increasing their focus on ways to reduce the carbon footprint of materials and offer more sustainable products. Consequently, companies are looking at new and innovative technologies to produce pX from renewable biomass resources rather than from crude oil, to enable production of a 100% bio polyester product. This report focuses catalytic fast pyrolysis (CFP) of lignocellulose to bio-oils which are refined to bio-pX with the objective to reduce carbon footprint in comparison to petro-pX. There are other processes currently being developed for bio-pX, but a discussion of these processes are beyond the scope of this paper.

As the world is emerging from the global pandemic of 2020–2021, increasingly, big companies have turned their focus on sustainability and establishing aggressive targets to reduce the carbon footprint of their products and over time move toward a net-zero carbon profile. It was earlier in 2009 Coca-Cola announced their rollout of the PlantBottle™ [2]. Coca-Cola's mission is to reduce reliance on non-renewable resources, and reduce CO2 emission in polyethylene terephthalate (PET). Currently, only 30% of the PET in PlantBottle™ is made from bio-MEG. A commercialized process for bio-PTA process would enable Coca-Cola (and others) to produce 100% bio-PET PlantBottle™. Advantageously, bio-PET production would be a "drop-in" into existing PET assets. By 2012, Coca-Cola, Ford, Heinz, Nike, and Procter & Gamble founded the "Plant PET Technology Collaborative" and announced their mission [3]:

"PTC members are committed to supporting and championing research, expanding knowledge and accelerating technology development to enable commercially viable, more sustainably sourced 100% plant-based PET plastic while reducing the use of fossil fuels". Similarly, Danone, Nestlé Waters, Origin Materials and PepsiCo formed the NaturALL Bottle Alliance in 2018. Since Coca-Cola's 2009 announcement, many have gravitated to the challenge to develop bio-PTA.

The reduced carbon footprint of bio-pX, and consequently bio-polyester, can contribute to meeting these carbon reduction goals for companies that participate in the polyester value chain, and this is the key business driver behind the increasing interest in routes to bio pX. The bottom line: once bio-pX is available, oxidation of bio-pX to bio-PTA would produce 100% bio-PET.
