Published: November 17, 2011 r2011 American Chemical Society 5755 dx.doi.org/10.1021/ef201428a | Energy Fuels 2011, 25, 5755–5766 ARTICLE pubs.acs.org/EF Preliminary Assessment of Synthesis Gas Production via Hybrid Steam Reforming of Methane and Glycerol Ragavendra P. Balegedde Ramachandran, Guus van Rossum,* Wim. P. M. van Swaaij, and Sascha R. A. Kersten University of Twente, Faculty of Science and Technology, Thermo-Chemical Conversion of Biomass, P.O. Box 217, 7500 AE Enschede, The Netherlands ABSTRACT: In this article, hybrid steam reforming (HSR) of desulphurized methane, together with crude glycerol, in existing commercial steam reformers to produce synthesis gas is proposed. The proposed concept consists of a gasifier to produce vapors, gases, and char from crude glycerol, which is coupled with a pre-reformer to further convert the vapors into gases using a steam reforming catalyst. These gases are mixed with methane and subsequently reformed to synthesis gas (CO + H 2 ) in a primary reformer, using a steam reforming catalyst. In the present work, gasification, steam, and hybrid reforming of glycerol are reported. The total product distribution (gas, vapor, and char) of pure and crude glycerol gasification was quantified at different reaction temperatures at very high heating rates (atomization, ∼10 6 °C/min). With pure and neutralized crude glycerol, no char formation was observed. However, with crude glycerol and pure glycerol doped with KOH, a significant amount of char on carbon basis (∼10%) is produced. The results obtained here show that KOH present in glycerol was responsible for polymerizing higher molecular components formed during thermal degradation. Steam reforming of pure and neutralized crude glycerol was studied at different process conditions in the presence of commercial reforming catalysts. Pure glycerol was easier (in terms of catalyst activity) to reform when compared to neutralized crude glycerol at high temperature (800 °C). The results from the steam reforming of neutralized crude glycerol show that the loss of catalyst activity was due to the presence of organic impurities such as FAMEs, diglycerides, and triglycerides. The proposed HSR concept was demonstrated using 28 wt % pure glycerol and 72 wt % methane (on C 1 basis) in a two-stage fixed bed reformer at 800 °C using commercial steam reforming catalyst. ’ INTRODUCTION Over the past several years, there has been an increasing interest in the use of biodiesel as a supplement to the traditional fossil fuels. With the ever-increasing production of biodiesel, a surplus of crude glycerol, which is a byproduct from the transesterification process, is available for further processing. The crude byproduct stream typically comprises of a mixture of glycerol, methanol, inorganic salts (mainly catalyst residue), free fatty acids, and fatty acid methyl esters in varying quantities. Purification is required to transform the crude glycerol to a usable state for food and pharmaceutical applications. As a first step in purification, excess methanol is distilled and reused for the trans- esterification process. An acid neutralization step is required to purify crude glycerol further, to convert alkali hydroxide catalyst into its salts (e.g., chlorides), typically around 5% present in the crude. 1 The combination of high methanol prices and low crude glycerol prices has made the conversion of crude glycerol to methanol via steam reforming economically attractive. 1 To take advantage of the existing natural gas steam reformers, there is a possibility to replace natural gas by a fraction of crude glycerol on carbon basis. This concept is proposed here as “hybrid steam reforming” to utilize either a direct crude or purified/neutralized crude glycerol. The hybrid steam reforming process consists of the following stages: (1) Gasification: the controlled atomization of crude glycerol into small droplets (∼100 μm) in a gasifier around 500 °C. This leads to the production of vapor, gases, and char via thermal decomposition. (2) Steam reforming: the vapor pro- duced from the gasifier can be pre-reformed using a commercial reforming catalyst. Adhikari et al. 2 reported that a minimum temperature of ∼600 °C is required to convert glycerol into gases. This step is similar to pre-reforming of naphtha/natural gas. In the case of naphtha and natural gas, higher hydrocarbons are partially reformed to produce gases whereas in the case of glycerol, vapors (oxygenates) are reformed to produce gases. (3) Hybrid steam reforming: the product gas obtained from the pre- reforming step can be mixed with desulphurized methane and reformed in the primary reformer. Because this is similar to natural gas reforming, a high temperature of ∼800 °C is preferred for this step. The whole concept is summarized in Figure 1a. Hybrid reforming can be beneficial in many ways: • The steam necessary for the primary reforming (molar S/C ∼ 3) can be completely/partly utilized in the pre-reforming step (S/C ∼ 515, depends on glycerol fraction). Here, S/C is defined as the ratio of the total moles of water added, including the water content of the glycerol, over the moles of carbon present in the glycerol. Therefore, no additional steam is required for the process. • Figure 1b summarizes the S/C required for a specific fraction of crude glycerol (by wt % on C 1 basis) available for hybrid steam reforming. For instance, to process 30 wt % of glycerol on carbon basis, a S/C up to 10 is necessary in the Received: September 19, 2011 Revised: November 9, 2011