Transformation and catalytic effects of sodium during coal pyrolysis

Fig. S1. A two-stage gasification device.¹ In the pyrolyser, solid residues from the cyclone separator heat the fresh coal from the storage bunker. The coal is then pyrolyzed without carrier gas. The char is transferred into the gasifier by shaking and gravity, and then reacts with gaseous agents in the gasifier. The gasification yields are separated by the cyclone separator. During the pyrolysis of fresh coal, the coal particles are stacked at bottom of the pyrolyser and there is no carrier gas flowing through the interstices between the coal particles. In other words, the reaction condition here is similar to that in a horizontal fixed-bed reactor.

Figure S2. Contents of sodium and anions in raw coal on dry coal basis. The contents of NO₃⁻ and CH₃COO⁻ were much lower than that of any other anion.

Figure S3. Curve-fitting of Raman spectrum of H-1-char-900 produced from pyrolysis of H-form-1 coal at 900°C. The G band represents aromatic ring breathing, rather than the fundamental vibration, in highly disordered carbon material.² The D band represents medium- to large-sized (≥ 6) aromatic ring systems in amorphous carbon structures.² The G_R, V_L, and V_R bands between the G and D bands represent relatively small aromatics with three to five fused benzene rings.³ The S_L and S bands represent sp³-rich structures (Table S1).

Figure S4. Scanning electron microscopy images of H-1-chars and H-2-chars derived from pyrolysis of H-form-1 and H-form-2 coals, respectively (× 10000).

Figure S5. Raman spectra of chars prepared at 500, 700, and 900°C. (a) H-1- and Na₂SO₄-chars, (b) normalized Raman spectra of H-1- and Na₂SO₄-chars, and (c) normalized Raman spectra of H-2- and Na-chars.

Table S1. Summary of Raman peak/band assignments