Catalytic Gas Conditioning:  Application to Biomass and Waste Gasification

Abstract

Catalytic gas conditioning is a key step in producing clean syngas via gasification of heterogeneous materials. Our work has focused on the steam re-forming of naphthalene and orthodichlorobenzene as prototypes of polyaromatic hydrocarbons (PAHs) and halogenated aromatics. Subsequently, we have studied the conversion of tar present in the syngas derived from biomass and waste gasification. Steam re-forming of naphthalene was initially studied over a UCI GB-98 commercial catalyst in a fixed bed reactor operated at atmospheric pressure, in the temperature range 873-1123 K, with residence times of 0.31-0.82 s and steam to naphthalene molar ratios of 10-22. Although the catalyst is efficient, it suffers from a progressive drop in activity due to coke formation as well as weight loss (35% weight loss after 24 h on stream). To overcome deactivation and catalyst weight loss, a robust catalyst formulation has been developed. It has demonstrated excellent activity as well as reasonable time-on-stream and easy regeneration without significant loss of activity. Total conversion of naphthalene and dichlorobenzene has been observed at 1023 and 1123 K, respectively. The yields of dry gas in both cases have been higher than 90%. After 60 h on stream, the catalyst weight loss is less than 5%. This catalyst has also performed efficiently in the conversion of tar present in the producer gas from air gasification of biomass and mixed wastes.

Evaluation of different oxygen carriers for biomass tar reforming (I): Carbon deposition in experiments with toluene

“…Because of the complex composition of real tar, several researchers have studied tar decomposition reactions using biomass tar model compounds such as: anthracene [25], benzene [25][26][27][28][29][30][31], cyclohexane [32], 1-methyl-naphthalene [26,33], naphthalene [25,27,28,[34][35][36][37][38][39][40][41][42][43][44][45], n-heptane [26,[46][47][48], phenol [49], pyrene [25] and toluene [10, 11, 25-28, 31, 50-57].…”

Catalytic Pyrolysis/Gasification of Refuse Derived Fuel for Hydrogen Production and Tar Reduction: Influence of Nickel to Citric Acid Ratio Using Ni/SiO2 Catalysts

“…Recent tar determinations have reported the use of optical methods based on laser induced systems [17], specifically fluorescence signals are applied with the flexibility of achieving in-situ or online tar measurements; however the elevated cost of this technology might reduce its further application, compared with the Tar Protocol [12,13]. Besides the tar collection and determination, further methods to reduce tar content in the produced gas have been also analysed [18][19][20][21]. For example, different catalysts are commonly used during the catalytic steam reforming process, as some of them exhibit high activities for tar elimination and gas upgrading during the gasification process [8].…”

Waste Gasification by Thermal Plasma: A Review

“…The main solutions proposed in the scientific literature are to optimize the design of the gasification reactor, its operating parameters (temperature, pressure, oxidizing agent/waste ratio, residence time …), by adding catalyst or by plasma treatment [46][47][48][49][50][51][52][53][54][55][56][57]: The gasification temperature (> 1 200 K -1 300 K) has a beneficial effect to minimize the tar quantities and allows destroying the aromatics without a catalyst [47,51]. A reduction of more than 40 % in tar yield has been reported when the temperature was raised from ~ 1 000 K to ~ 1 200 K.…”

“…Catalysts like dolomite, limestone, olivine sand, bauxite, lanthanum, alumina, nickel aluminate, cobalt, natural clay minerals and iron minerals can be used to optimize the tar reforming at high temperature [46,[53][54][55][56][57]. It is an efficient method for the tar destruction but this primary method can be very expensive in function of the catalyst used and its consumption.…”