Biomass-rich Waste Conversion into Drop-in Fuels

Lead Proponent: Enerkem Inc.
Location: Montréal, Quebec
ecoEII Contribution:  $ 729K
Project Total:  $ 1.46M

Project Background:

Each year, around 34 million tonnes of bio-derived wastes are generated in Canada, a large portion of which go to landfill sites.  However, these waste materials are a source of carbon which can be utilized in the production of renewable hydrocarbon biofuels and chemicals.  Enerkem is a company based in Montreal who has developed a proprietary gasification technology capable of transforming low-value biomass residues into ultrapure synthesis gas, or “bio-syngas”.  Bio-syngas can be subsequently converted to liquid biofuels which are chemically identical to hydrocarbon fuels, and as such, are referred to as “drop-in” fuels.  They are similar to petroleum gasoline, diesel, or jet fuel in chemical makeup and are therefore considered fully infrastructure-compatible fuels (ready to "drop-in" to existing infrastructure).

To that end, Enerkem proposed the “Biomass-rich Waste Conversion into Drop-in Fuels” project for ecoEII funding.  EcoEII awarded the Project $729K to develop catalytic processes that convert synthesis gas obtained from thermal gasification of non-recyclable municipal solid waste (MSW) into “drop-in” renewable fuels.  The use of MSW as feedstock brings about added benefits of reducing waste going to landfill and emissions from landfills.

Results

Dimethyl ether (DME) is the simplest aliphatic ether.  Synthesis gas produced by gasification of the waste can be converted into DME by one of two approaches:  (1) methanol synthesis and the dehydration reaction are carried out simultaneously in the same reactor using a bi-functional catalyst to yield DME in one pass; and (2) syngas is converted to methanol, then the methanol is converted into DME through a methanol dehydration reactor using a dehydration catalyst. Experimental work performed using both approaches yielded similar results - up to 307 kg of DME per Bone Dry Metric Ton (BDMT) of biomass.  Such yields are consistent with secondary data found through literature review.

Bench tests were performed to convert DME into olefins (mainly propylene, with some ethylene and butene).  Conversion was carried out using ZSM-5 zeolite as the active catalyst.  ZSM-5 zeolite was prepared in-house, as an “extruded” pellet.  A parametric study was conducted to determine the optimum operating conditions and feed composition.  Results indicated that high temperature and low weight hourly space velocity (WHSV) had greater effect on selectivity of olefins.  Furthermore, low methanol concentration and high water content in the feed increased selectivity of olefins.  The resulting yield was 0.36 g-propylene /g-methanol (MeOH), which is comparable to the yields reported by other companies working on propylene synthesis from methanol, using DME as intermediate.  It was determine that Enerkem’s method of propylene synthesis was effective.

The next stage involved benching testing of the oligomerization of olefins.  Results indicated that olefins oligomerization is most suitable for gasoline production.  The maximum gasoline yield obtained was 99 g-gasoline/g-olefins.  The gasoline composition is very similar to that of commercially available gasoline and had a motor octane number (MON) of 80 without octane enhancers.  Diesel was also produced through olefins oligomerization.  However, catalyst deactivation occurred very quickly, and using fixed bed reactor would therefore not be suitable for a commercial plant application.  Lastly, jet fuel was produced through propylene oligomerization, followed by distillation at 80°C and hydrogenation.  The highest yield reached was 0.42 g-jet-fuel/g-olefins.  The jet fuel produced has the same composition as JP-4.

Benefits to Canada:

Successful production of drop-in fuels from biomass-rich waste would grow the biofuels and bio-products sector in Canada by introducing new biogenic carbon fuels.  The use of MSW as feedstock for the production of drop-in fuel diverts waste going to landfill and reduces greenhouse gas (GHG) emissions from landfill operations.

Next Steps

At present (2016), economics do not favour an integrated plant that converts MSW into drop-in fuels, at realistic capacities comparable with available MSW.  However, a “hub and spoke” approach whereby methanol is produced from MSW in satellite plants and transported to hubs for upgrading to fuels, merits attention.  Further RD&D is needed to move the technology up the innovation chain - cost reduction, value engineering and market assessment.

Please contact the ecoENERGY program to obtain a copy of the Enerkem Inc. Completion Report.