Abstract This paper shows the results of the solid-state synthesis of mullite from spent catalysts discarded from fluid catalytic cracking (FCC); the catalysts are mainly composed of silica and alumina but are polluted with SO X , forming a non-crystalline network. The synthesized mullite was used as a feedstock to thermally spray a coating onto a silica-alumina refractory brick, and its chemical resistance at high temperature was subsequently evaluated by contact with K 2 CO 3 at 950 °C. Initially, the spent catalyst was thermally treated for 2 h at 600, 900, and 1200 °C to eliminate the SO X pollutant. The heat treatment at 1200 °C completely removed the SO X in the sample. Additionally, four thermal processes were performed by heating the spent FCC catalyst in an electrical furnace to 1500 and 1600 °C and by using an oxyacetylene flame to synthesize mullite. Thermal treatments at 1500 °C were performed with and without alumina added to the spent FCC catalyst, whereas those conducted at 1600 °C and using a flame were performed using only added alumina. In the powders thermally treated at 1500 °C, silica-rich mullite (3Al 2 O 3 .2SiO 2 ) accompanied by an excess of alumina or silica was obtained with or without alumina added, respectively. In contrast, the materials treated at 1600 °C formed alumina-rich mullite (2Al 2 O 3 .SiO 2 ), which was accompanied by an excess of alumina. Mullite was not synthesized in the flame-heated powder. The silica-rich mullite accompanied by an excess of alumina was used as feedstock powder to modify the surface of a refractory brick, improving its resistance to chemical attack by K 2 CO 3 at high temperature.

中文翻译：

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从用于制造耐火砖涂料的废催化剂固态合成莫来石

摘要 本文展示了从流化催化裂化 (FCC) 废弃的催化剂中固态合成莫来石的结果；催化剂主要由二氧化硅和氧化铝组成，但被SO X 污染，形成非结晶网络。合成的莫来石作为原料在硅铝耐火砖上进行热喷涂涂层，随后通过在950℃下与K 2 CO 3 接触来评估其在高温下的耐化学性。最初，废催化剂在 600、900 和 1200 °C 下热处理 2 小时以消除 SO X 污染物。1200 °C 的热处理完全去除了样品中的 SOx。此外，通过在电炉中将废 FCC 催化剂加热至 1500 和 1600 °C 并使用氧乙炔火焰合成莫来石，进行了四个热处理过程。在 1500 °C 下进行热处理，在废 FCC 催化剂中添加和不添加氧化铝，而在 1600 °C 下进行并使用火焰进行的热处理仅使用添加的氧化铝进行。在 1500 °C 下热处理的粉末中，分别在添加或不添加氧化铝的情况下获得伴有过量氧化铝或二氧化硅的富含二氧化硅的莫来石 (3Al 2 O 3 .2SiO 2 )。相比之下，在 1600 °C 处理的材料形成了富含氧化铝的莫来石 (2Al 2 O 3 .SiO 2 )，伴随着过量的氧化铝。火焰加热粉末中未合成莫来石。