Ethylene, biomass-derived

As discussed in this book (Chapter 2, for example) a main difference between fossil fuels and biomass as feedstocks is that in the former case the functionalization of base chemicals obtained from the oil (ethylene, propylene, aromatics, etc.) occurs essentially by introduction of heteroatoms, while in the case of biomass-derived based chemicals (glycerol, for example) it is necessary to eliminate heteroatoms (oxygen, in particular). Consequently, the catalysts required to develop a petrochemistry based on bio-derived raw materials need to be discovered and cannot simply be translated from existing ones, even if the knowledge accumulated over many years will make this discovery process much faster than that involved in developing the petrochemical catalytic routes. 

The glow electrolysis technique (electrolysis with an anode immersed in the solution and the cathode above the surface) at 600-800 V dc and 300-500 mA converts a solution of starch into ethylene, methane, hydrogen, and both carbon mono- and dioxides.323 Electrochemical methods for converting polysaccharides and other biomass-derived materials have been reviewed briefly by Baizer.324 These methods are mainly oxidations along a potential gradient, which decreases the activation energy of the reactants. Starch in 5 M NaOH solution is oxidized on platinum electrodes to carboxylic acids with an activation energy of about 10 kcal/mol. In acidic media oxidation takes place at C-l followed by decarboxylation and oxidation at the C-2 and C-6 atoms.325... 

In addition to bio-based polyesters such as poly(lactic acid) (PLA), polyhydroxyalkanoates (PHAs), and poly(ethylene furanoate) (PEE), all based upon biomass-derived building blocks that have a structure different from today s commercial petrochemical-based polyesters, biobased polyesters can be developed having an identical structure to well-known petrochemical based polyesters. A very important class of such drop-in type bio-based polyesters are represented by polyesters based upon either isophthalic acid or terephthalic acid, such as PET,... 

Lactic acid is currently produced by fermentation of carbohydrates and is rme of the high potential and versatile biomass-derived platform chemicals, leading to various useful polymer products. PLA is produced by ROP of lactide (derived from lactic acid) and exhibits mechanical properties similar to poly(ethylene terephthal-ate) and polypropylene. Representative examples discussed herein included the synthesis of highly stereo-controlled PLAs, such as isotactic, heterotactic, and syndiotactic PLA materials, rendered by different catalyst/initiator systems. 

Another 100% bio-based alternative polyester well suited for beverage bottles and likely to be economical compared to PET is poly(ethylene fuianoate) (PEE) (Byun and Kim, 2014). Biomass-derived saccharides (such as suCTOse) can be converted into alkoxymethyl furfural, which is oxidized into EDCA. The EDCA can be condensed with EG to yield PEE polymer with a higher Tg (Sb C), a lower Tm (235°C), and a higher modulus compared to PET. Its barrier properties are also reported to be superior to those of PET. "... 

Sun, J.Y., Liu, H.C. 2011. Selective hydrogenolysis of biomass derived xyUtol to ethylene glycol andpropylene glycol on supported Ru catalysts. Green Chem. 13,135-142. 

Because oil and gas ate not renewable resources, at some point in time alternative feedstocks will become attractive however, this point appears to be fat in the future. Of the alternatives, only biomass is a renewable resource (see Fuels frombiomass). The only chemical produced from biomass in commercial quantities at the present time is ethanol by fermentation. The cost of ethanol from biomass is not yet competitive with synthetically produced ethanol from ethylene. Ethanol (qv) can be converted into a number of petrochemical derivatives and could become a significant source. 

Methanol is currently produced from syngas, which has been enriched with C02 and is derived from either a fossil fuel or biomass. A better approach might consist of the direct hydrogenation of pure C02, whilst transesterification with ethylene carbonate implies that ethylene, derived from oil refineries, should be used as the raw material. 

Derivation (1) From ethylene by direct catalytic hydration or with ethyl sulfate as intermediate (2) fermentation of biomass, especially agricultural wastes (3) enzymatic hydrolysis of cellulose... 

Application The UOP/HYDRO Methanol-to-Olefins (MTO) Process produces ethylene and propylene from methanol derived from raw materials such as natural gas, coal, petroleum coke or biomass. 

Ethylene for the manufacture of polyethylene is derived from cracking various components of petroleum oil such as the gasoline fraction, gas oil, or from hydrocarbons such as ethane. While petroleum remains the predominant source of the monomer at the present time, it can also be produced using biomass. In fact ethylene has been commercially derived from molasses, a by-product of sugar cane industry, via the dehydration of ethanol. 

Other interesting and growing enviromnentally friendly indnstries which ACOMP may be applied to are biofuels and green polymers made from renewable feedstocks such as ethanol-derived ethylene and other processes. ACOMP may eventnaUy be nsed to monitor fermentation processes to gange conversion of biomass to the active biofuel or chemical feedstock. This is a completely novel and untested application for the technology, but could be of substantial commercial and enviromnental benefit. 

---