Core Technology for Green Methanol/Jet Fuel: Biomass Pure Oxygen/Steam Gasification to Syngas Completes 10,000-Ton-Level Industrial Trial

Utilizing biomass as a carbon source, coupled with photovoltaic electrolysis to produce “green hydrogen,” and synthesizing green jet fuel and green methanol through catalytic processes has become a global research focus in green, low-carbon technology and an emerging direction for the energy and chemical industries. This approach is also a critical technology for advancing the “carbon neutrality” goal. Among the key technologies involved—such as syngas production, purification, and catalytic synthesis—biomass gasification to syngas remains a bottleneck in the industrialization chain, both domestically and internationally. Due to significant differences between biomass and coal in fuel composition, grindability, slurry-forming properties, and ash characteristics, large-scale coal gasification technologies (primarily entrained-flow gasification), despite their extensive industrial applications, are unsuitable for biomass fuels. Fluidized-bed-based large-scale biomass gasification is considered the most viable technical option. However, it requires solving the “tar” challenge in biomass gasification and purification while advancing the scale-up and industrial application of biomass-to-syngas operating conditions.

Professor Xu Guangwen’s team at Shenyang University of Chemical Technology, in collaboration with Jinan Huangtai Coal Gas Furnace Co., Ltd., has innovatively developed a 10,000-ton-per-year industrial-scale fluidized-bed two-stage gasification pilot plant. This system decouples and reconstructs fuel pyrolysis and char gasification/tar cracking reactions using a fluidized-bed reactor, establishing a complete cycle of biomass char “catalysis” and “regeneration” (see Figure 1). By leveraging thermal cracking, oxidative cracking, and high-temperature char catalytic cracking in a fast fluidized-bed reactor, the technology achieves deep tar removal, meeting the technical goal of producing low-tar combustible gas or syngas from biomass gasification. Capitalizing on the advantages of efficient mass transfer and reaction in fluidized-bed systems, this innovative biomass gasification technology exhibits unique adaptability to high-moisture, low-calorific-value biomass fuels.

Figure 1: Schematic of the two-stage fluidized-bed gasification process for ultra-low-tar combustible gas/syngas production.

The two-stage fluidized-bed air gasification technology for combustible gas production has already been successfully applied to biomass waste from light industrial processes, such as Chinese medicine residues and distiller’s grains. Industrial-scale projects with capacities ranging from 10,000 to 50,000 tons per year have been established in Henan, Sichuan, Shandong, and Anhui, achieving an internationally advanced tar content of below 50 mg/Nm³ in the produced gas. The primary objective of this industrial trial was to validate the technical feasibility and operational stability of the two-stage fluidized-bed gasification process under atmospheric pressure, using various biomass feedstocks for oxygen-enriched gasification (oxygen+air+steam as the gasifying agent) to produce high-quality combustible gas and pure oxygen gasification (oxygen+steam) to produce syngas. The trial employed pelletized rice straw and corn stalk fuels from Shandong (see Table 1). By optimizing reaction conditions and oxygen/steam supply, the gasification system maintained stable temperatures between 750–880°C, with the longest continuous operation exceeding 110 hours (see Figure 2).

Table 1: Biomass fuels and their properties used in the industrial trial of two-stage fluidized-bed gasification.

Note: The feedstock used in the demonstration was on an as-received basis; *fixed carbon content was calculated by difference.

Figure 2: Evolution of key operating parameters during biomass pure oxygen/steam two-stage fluidized-bed gasification for syngas production.

The corresponding gas production results are shown in Figure 3. The continuous operation achieved a feed rate of 2,400–2,800 kg/h, with an excess air coefficient of 0.3–0.4 and oxygen concentration in the gasifying agent controlled at 30–40%. The system demonstrated excellent stability during transitions between oxygen-enriched and pure oxygen gasification, feedstock switches, and adjustments in processing capacity. By varying operational parameters, the calorific value and effective gas content of the product gas could be tuned within a certain range. As shown in Figure 3, the torch exhibited a bright yellow flame at high calorific values (exceeding 2,400 kcal/Nm³ when using N₂ as the recirculation gas), while a pale blue flame indicated high hydrogen content (up to ~40 vol.% H₂ at the outlet). The effective syngas (CO+H₂) fraction reached ~65%, with ~5% methane. The system also showed strong adaptability to low-quality biomass fuels like corn stalk 2, though high ash content notably reduced gas yield. The cold gas efficiency of biomass remained stable at over 80% throughout the trial. In practical applications, using superheated steam as the recirculation gas could further optimize gas quality and increase the effective gas fraction. Analysis of fly ash collected by bag filters showed that carbon content could be controlled below 30% during stable operation (see Table 2).

Figure 3: Continuous operation results of biomass pure oxygen/steam two-stage fluidized-bed gasification for syngas production.

Table 2: Fly ash analysis from the industrial trial of two-stage fluidized-bed gasification.

Note: Fly ash was analyzed on an air-dried basis; *fixed carbon content was calculated by difference; carbon content was determined via elemental analysis.

During continuous testing, a gas/tar sampling port was installed in the pipeline between the cyclone separator and the high-temperature air preheater. A suction pump drew gas samples through acetone scrubbing to collect tar while purifying the gas for composition analysis (see Figure 4). Sampling lasted ~10 hours, with tar content analyzed via acetone absorption. Results showed tar content of 1.58 g/Nm³ for corn stalk and 0.58 g/Nm³ for rice straw. While these values are specific to the pilot setup, full-scale industrial systems could further reduce tar through staged oxygen supply and optimized gasification temperatures. The trial confirmed that water scrubbing is necessary to meet catalyst requirements for methanol/jet fuel synthesis, with the validated gasification technology capable of maintaining tar levels within acceptable limits.

Figure 4: Tar content analysis in product gas from corn stalk and rice straw gasification.

In summary, the trial demonstrated the technical advantages of two-stage fluidized-bed gasification, including high-quality syngas production, stable operation, low tar, and broad fuel adaptability. It verified the feasibility of this novel biomass-to-syngas technology and its readiness for further scale-up. Notably, this represents the longest continuous operation, most diverse biomass feedstock testing, lowest tar content, and highest effective syngas yield reported in China to date for biomass gasification.

The validated two-stage fluidized-bed gasification process is simple (see Figure 1) and builds on dual fluidized-bed reactor systems, which have well-established industrial applications globally. This positions the technology as a strong contender for future “green methanol/jet fuel supply chains.” Following the successful trial, the team will accelerate collaborations with domestic and international enterprises to industrialize atmospheric-pressure fluidized-bed two-stage gasification while developing pressurized systems, addressing current challenges in biomass-based green synthesis technologies.

Correspondence 1: Zhennan Han (hanzhennan1989@163.com), Chao Wang (wangchao_0703@163.com), Institute of Energy and Chemical Industry Technology, Shenyang University of Chemical Technology, Ministry of Education Key Laboratory of Specialty Resource Chemistry and Materials, No. 11, 13th Street, Economic Development Zone, Shenyang, Liaoning, China

Correspondence 2: Liguo Zhou (18340065888@139.com), Jinan Huangtai Coal Gas Furnace Co., Ltd. / Jinan Haiyao New Energy Equipment Co., Ltd., Room 901, Block B, Shimao Square, Quancheng Road, Daminghu Street, Jinan, Shandong, China