A project is carried out to develop a process for tar elimination downstream of a gasifier making use of cheap and active materials as catalysts. In the first stage of the project, screening of catalysts was carried out in a fixed-bed tubular reactor. The results of the fixed-bed experiments will be used in the design of the process. This paper presents a review of the various types of catalysts that have been used in several research works to reduce the tars in the producer gas derived from the biomass gasification process. The catalysts are divided into two classes according to their production method:  minerals and synthetic catalysts. A summary of the review and recommendations for good catalyst candidates and future work are also provided.

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Oil shale is an important possible solution to the problem of energy in Jordan. To explore the technical and the economic feasibility of oil shale deposits, numerous samples are analyzed using the standard Fischer Assay (FA) method. However, it would be useful to develop faster, cheaper, and reliable methods for determining the oil content of oil shale. Therefore, the aim of this work was to propose and investigate rapid analytical techniques for the screening of oil shale deposits and to correlate them with the FA method. The Omari deposit located east of Jordan was selected as a case study for analysis using thermogravimetric analysis (TGA) coupled with Fourier-transform infrared (FTIR), differential scanning calorimetry (DSC), elemental analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) analysis. Results obtained from the TGA method were linearly correlated with FA with high regression factor (R2 = 0.99); a quadratic correlation (R2 = 0.98) was maintained between the FA and the elemental hydrogen mass content, and a quadratic correlation (R2 = 0.97) was found between the FA and the aliphatic hydrocarbons (FTIR peak at 2927 cm−1) produced in the pyrolysis zone. Although other techniques were less correlated, further investigation might lead to better results. Subsequently, these correlated techniques can be a practical alternative to the conventional FA method when, in particular, specific correlation is made for each deposit.

Catalytic tar removal is one of the main challenges restricting the successful commercialization of biomass gasification. Hot gas cleaning using a heterogeneous catalyst is one of the methods used to remove tar. In order to economically remove tar, an efficient low-cost catalyst should be applied. Biomass char has the potential to be such a catalyst. In this work, the reactor parameters that affect the conversion of a model tar component “naphthalene” were investigated employing an in situ thermogravimetric analysis of a fixed bed of biomass char. The following reactor and catalyst parameters were investigated: bed temperature (750 to 900 °C), gas residence time in the char bed (0.4 to 2.4 s), char particle size (500 to 1700 μm), feed naphthalene concentration, feed gas composition (CO, CO2, H2O, H2, CH4, naphthalene, and N2), char properties, and char precursor. It was found that the biomass char has a high activity for naphthalene conversion. However, the catalytic performance of the biomass char was affected by the gasification reactions that consumed its carbon, and the coke deposition that reduced its activity. Furthermore, high ash and iron contents enhanced char activity. The results of this work will be used in the design of a process that uses biomass char as an auto-generated catalyst in the gasification process.