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Converting wastepaper to biocrude and hydrogen

12 May 2013

Tungal
Biocrude compounds, product gas and reaction pathways from APR of wastepaper at 250 °C in presence of 5 wt % Ni(NO3)2 catalyst. Credit: ACS, Tungal and Shende. Click to enlarge.

A pair of researchers at the South Dakota School of Mines & Technology have demonstrated homogeneously catalyzed subcritical aqueous phase reforming (APR) of wastepaper to produce biocrude and hydrogen. A paper on their work is published in the ACS journal Energy & Fuels.

Wastepaper can be a combination of newspaper—a lignocellulosic biomass containing cellulose (62%), hemicellulose (16%), and lignin (16%)—and used office printing papers which consist of mainly cellulose (85−99%) and negligible (0.4%) lignin. Using a homogeneous Ni(NO3)2 catalyst, they produced about 44 wt % biocrude from wastepaper slurry at 250 °C after 120 minutes of reaction time. The biocrude contained ∼1 wt % HMF/furfural, 7.5 wt % sugars, 49.1 wt % acids, and 42.4 wt % oxygenated hydrocarbons.

The product gas showed a maximum of about 0.2 mol % and 3.75 mol % H2 (17.7 mol % N2 free basis) after 120 min of reaction time at 225 and 250 °C, respectively, along with CO, CH4, and CO2. At a higher reforming temperature of 275 °C, 10.2 mol % H2 was observed with 51.9 wt % biocrude production.

Production of paper products is expected to increase to 4.6 × 108 tonnes by 2015, a 28% increased from 2005 levels, the authors noted. The current preferred way of managing wastepaper disposal is via landfilling and/or incineration; one hindrance to recycling activity is the difficulty in manufacturing high quality paper products because of higher pulp fiber content. The researchers decided to explore the potential for converting wastepaper to fuels.

Biocrude and H2 can be produced from thermochemical processing of biomass using gasification, pyrolysis, fast pyrolysis, and aqueous phase reforming under subcritical and supercritical conditions. Among these processes, aqueous phase reforming or hydrothermal treatment has several advantages, which include lower energy consumption, direct utilization of biomass without any pretreatment or drying and lower tar and char formation, as compared with other thermochemical processes where significant biochar and tar are generally produced by polymerization of dehydrated products.

The biocrude generated from different biomass feedstocks under hydrothermal conditions has shown lower oxygen content (10−20%) and higher heating value (30−36 MJ/kg) as compared with a biomass, which has higher oxygen content and lower heating value. In addition to biocrude, aqueous phase biomass reforming is also capable of generating high energy density fuel, H2 (143 MJ/kg).

It is to be noted that under subcritical conditions, the dielectric constant of water is significantly lower, which allows solubilization of organic compounds whereas ionization constant is approximately 3 orders of magnitude higher than at ambient conditions providing acidic medium for the hydrolysis of biomass compounds. Consequently, subcritical water not only serves as a reaction medium but also acts as reactant leading to liquefaction of a biomass that proceeds through a series of chemical modifications involving depolymerization, solvolysis, and chemical and thermal decomposition of monomers into smaller molecules.

This aspect of subcritical water processing of biomass is attractive as it encompasses several competing reaction pathways converting biomass to liquefied biocrude and gaseous fuels such as H2 and/hydrocarbons. The use of a catalyst further influences the production of biocrude and gaseous fuels. Among different feedstocks investigated so far, the information on homogeneously catalyzed subcritical aqueous phase reforming of wastepaper for biocrude and H2 generation is missing in the literature.

—Tungal and Shende

In their experiments, the team prepared slurries of 15 g wastepaper in 150 mL of distilled water using 5 wt % catalyst for loading in the reactor. The reactor was pressurized to 40 psi at room temperature with N2; temperature was varied between 200−275 °C. The reforming reaction was continued for 120 min and while the reaction was in progress, gas and liquid samples were withdrawn periodically and analyzed using gas chromatography (GC), gas chromatography mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), and total organic carbon (TOC) analyzer.

HPLC analysis of the resulting biocrude revealed presence of sugars such as cellobiose, xylobiose, glucose, and mannose and organic acids, which include formic, acetic, propionic, and lactic. GC-MS analysis of the biocrude identified 46 oxygenated hydrocarbons with >85% confidence level, which mainly include cyclic ketones and substituted cyclic ketones, quinone derivatives, phenols and substituted phenols, and aromatic alcohols.

Resources

  • Richa Tungal and Rajesh Shende (2013) Subcritical Aqueous Phase Reforming of Wastepaper for Biocrude and H2 Generation. Energy & Fuels doi: 10.1021/ef302171q

May 12, 2013 in Biomass, Fuels, Hydrogen Production | Permalink | Comments (12) | TrackBack (0)

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Comments

We really need an engineer on the job to give us a better idea of what these figures represent, but it is in any case a substantial resource.

Just looking at the gross figures and taking a ton of oil at 7 barrels, then the US consumes around 7 bn barrels of oil per year and the gross weight of the paper products produced is around 3 bn barrels by weight.

Of course, this does not include any of the losses, and as I said we need an engineer to give us any tighter estimate, but it is obvious that the resource is substantial in relation to demand.

Since this is just one source of hydrogen, it would appear that it is well able to do the job of providing for that part of transport needs which may be problematic for batteries (heavy goods, range extenders for batteries, or even pure fuel cell cars)

The article acts as if this or similar processes haven't been known for hundreds of years. So, they add some catalyst and get a specific set of products. Add a different one and get others, or, just do pyrolysis. Anyway, they say nothing about price or cost, or the capital equipment cost. I guess we're going to see billions in venture capital invested in this process right? Or, maybe not. Also, what is more valuable, paper or fuel?

@Brotherkenny4:
Yeah, you aren't interested in any progress and prefer to dump waste paper in landfill than use it as fuel.
Stick to your prejudices, and if you don't fancy it, ignore it.

I don't know about the requirements for turning said biocrude into conventional fuels, but the temperatures required for liquefaction of paper (250-275°C) are well within the capabilities of light-water nuclear powerplants.

The reactors take material that is about 10% paper by mass (presumably kraft paper/cardboard would also be a suitable feedstock).  If 30% of a plant's thermal output (roughly equal to rated electric output) was diverted during off-peak hours and heat recovery recaptures 70% of process heat, a 1 GW(e) plant could process about 300 kg of paper per second.  (I had to re-check that number.)

It looks like nuclear process heat is the answer to a big waste disposal problem.  How you keep the machinery from being gummed up by plastic report covers, glues and whatnot is another question.

We already recycle 90+% of our waste paper. Cascade Paper has been doing a good job in that domain for the last 30+ years.

Would the extraction of bio-fuels from waste paper be more advantageous than from Tar Sands or Shales? That's a good question?

As the world uses less and less paper, when news papers, magazines and books are digitized for tablets, waste paper could diminish by about 50% or more.

We already have to provide our own re-usable shopping bags for the last 5+ years. That reduced the use of plastic and paper bags. At the liquor stores we have 3 choices: 1) put the bottles in your pockets, 2) bring your own re-usable bag, 3) buy a re-usable bag ($0.75) on the spot.

Everybody has 6+ re-usable bags in the boot of their car.

Converting non-recyclable waste paper into liquid fuels and hydrogen is better than landfilling or burning it.

Yes, it would be acceptable for 'non-recyclable' waste paper, i.e. about 10% or so.

USA uses 748 lbs of paper/per capita/year or about 7 times the world average. The world uses 110 lbs/per capita/year.

Paper recycling varies a lot from place to place: (from 0% to 90%). Paper can be recycled 6 to 8 times but fibers get shorter each time. More new fibers are required to extend the number of recycle.

Recycling paper back into paper is only one route. It can also be used as cellulose insulation. This would not only make our houses more energy efficient but it would also keep the paper out of the landfill for as long (50 years?) as the house stands. And I believe cellulose insulation uses the post-recycled short fibers Harvey talked about.

Could be another good use for waste paper?

Here are some of the best insulators or bad heat conductors:

1. Silica Aerogel ...0.003
2. Argon gas.........0.016
3. Polyurethane foam..0.02
4. Dry Air...........0.024
5. Dry cotton........0.03
6. Expanded polystyrene ..0.03
7. Perlite...........0.031
8. Mineral wool......0.04
9. Cork..............0.04
10. Wood (oven dry)...0.04
11. Fiber glass.......0.045
12. PAPER.............0.05
13. Plexiglass........0.17
14. Rice hulls........0.359
15. Glass.............0.8

Silica and polyurethane foams are among the top for building insulation.

Yes, top from the stand point of r-value, but like I said in our earlier discussion about straw bale construction: All building materials have some embodied carbon but those made from wood and the like also sequester carbon.

Rice hulls
Cork
Cotton
Sheep's wool
Cellulose
etc.

Sorry ai_vin; loose cellulose made of 75% to 85% paper was not on my list and it should have been. It compares favorably with mineral wool, rock wool and fiber glass.

Wet sprayed cellulose does a better job but takes much longer to dry and may be subject to mold.

Fiber glass weight about three times less and may be more suited for ceilings.

Sprayed foams are superior and block humidity and water but cost more and create more GHG during manufacturing and installation.

All insulation materials seem to have a fair number of advantages and disadvantages.

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