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Hydrogen Production from Waste Tires Using a Catalytic Pyrolysis-Gasification Process

Elbaba
Schematic diagram of the two-stage pyrolysis-gasification experimental system. Credit: ACS, Elbaba et al.Click to enlarge.

A team at the University of Leeds (UK) is investigating hydrogen production from waste tires using a two-stage pyrolysis-gasification reactor and Ni-Mg-Al (1:1:1) catalyst. A paper describing their work was published online 10 June in the ACS journal Energy & Fuels.

The generation rate of waste tires is increasing, especially with the continued increase in production of cars and trucks, the authors note. In 2007, the amount of waste tires was about 4.6 million tonnes within the US; nearly 3.4 million tonnes in Europe; more than 1 million tonnes in Japan; and about 1 million tonnes in China.

Regional and national governments use a wide variety of methods to deal with waste tires. In Europe, the main methods for waste tire management are materials recovery (38.7%), energy recovery (32.3%), and retreading (11.3%). In the US, the main methods for waste tire management are tire-derived fuel (52.8%), ground rubber (16.8%), and civil engineering applications (11.9%).

The pyrolysis and gasification of waste tires for the production of liquid fuels, chemical feedstocks, activated carbons, and gases has been extensively researched. Recently, it has been suggested that the thermal decomposition of waste tire at high temperature might be an alternative for production of hydrogen in future energy systems.

Catalysts play an important role in pyrolysis-gasification processes for maximizing hydrogen production. Nickel-based catalysts have been reported as promising catalysts for tar removal and hydrogen production in steam gasification processes due to their good catalytic effect and comparatively low cost.

—Elbaba et al.

The pyrolysis-gasification was carried out in a two-stage fixed bed reactor, with a laboratory-prepared Ni-Mg-Al (1:1:1) used as a catalyst. The tire rubber sample was pyrolyzed in the first reactor, and the pyrolysis products were passed directly to the second reactor where steam catalytic gasification of the pyrolysis gases was carried out.

In addition, the team also investigated the elastomer constituents most commonly used in tires: natural rubber (NR), styrene-butadiene rubber (SBR), and butadiene rubber (BR).

Experiments were conducted at a pyrolysis temperature of 500 °C and gasification temperature of 800 °C. The results showed that the gas and hydrogen yield were greatly increased for the tire and elastomer constituents during pyrolysis-gasification with the introduction of steam and/or catalyst.

For example, without steam and catalyst (sand), only 24.4 wt % gas yield in relation to the mass of BR was obtained. The gas yield in relation to the mass of BR was increased to 32.9 wt % with the introduction of water at the gasification temperature of 800 °C without the catalyst. The gas yield in relation to the mass of BR was further increased to 153.4 wt % in the presence of the Ni-Mg-Al catalyst and steam.

There was a significant increase in H2 and CO concentrations as well as a consequent decrease in CH4 and C2-C4 concentrations when the Ni-Mg-Al catalyst was applied to the pyrolysis-gasification process.

Hydrogen production increased from 0.68 to 5.43 wt % for the catalytic steam pyrolysis-gasification of waste tire in the presence of Ni-Mg-Al catalyst. The highest hydrogen production (15.26 wt %) was obtained for the BR feedstock.

Resources

  • Ibrahim F. Elbaba, Chunfei Wu and Paul T. Williams (2010) Catalytic Pyrolysis-Gasification of Waste Tire and Tire Elastomers for Hydrogen Production. Energy Fuels, Article ASAP doi: 10.1021/ef100317b

Comments

HarveyD

Could this be done on a very large scale to use more of the accumulate tires around?

Could various feed stocks be used and various output be produced?

Eng. Poet will like this one.

sulleny

It's nice to recycle stuff like tires and get useable energy carrier out of the deal. But at 5-15% tops this will never be a H2 production solution.

There are far better albeit disruptive methods of producing massive volumes of H2 and O via water electrolizing. The more restrictions placed on this research - the faster it will come to surface. Lift restrictions of kind - desired order will prevail.

3PeaceSweet

Having a catalytic (plasma?) gasifier which you could add coal, biomass or waste into would be pretty handy. Even if it couldn't make a high quality gas, you could mix it with natural gas and use that for power generation.

HealthyBreeze

I tend to think that plasma gasification is better for destroying toxic compounds and generating syngas from waste streams. Since tires don't really biodegrade, this would be a preferred way to really recycle them and generate power.

Henry Gibson

The tires might be dissolved in ionic liquids and then can converted more directly to diesel by adding hydrogen produced by a reaction of water and carbon from coal.

Supercritical water will convert almost anything containing carbon to hydrogen and carbon dioxide.

Hydrogen is best produced by energy from fission.

..HG..

sulleny

The Idaho geothermal project claims to have supercritical water coming up... Reform steam to H2. But then you gotto compress and ship the stuff. In situ on demand seems a whole lot better.

wintermane2000

Well dont forget the h2 pipeline system is growing at an amazing pace right now. In 20 years or so it likely wont be an issue to pipe the hy2 across the nation.

Engineer-Poet

Hydrogen has the same pumping energy cost per molecule as methane, but about 1/3 the energy. It's not a good fuel for long-distance transmission.

While I like the idea of eliminating heaps of waste tires, I have to wonder if hydrothermal cracking back to monomers is better. Re-use is better than waste-to-energy.

wintermane2000

Well ep they manage to pipe h2 around 800 miles already and plan to expand the line greatly so they must be able to do it already now dont they?

SJC

Ground up tire material is now used in pavement. That technique was patented and now that has expired. There are lots of uses for materials that oil has gone into and we have not begun to reap the benefits from all of those yet.

Arne

SJC,

I was just gonna say that.

Adding recycled tyres to asphalt increases strength and durability and reduces noise. Recycling material as material is (nearly) always better than converting it to energy.

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