Understanding the role of tetramethyl urea for the synthesis of mesoporous alumina

Peer review under responsibility of The Ceramic Society of Japan and the Korean Ceramic Society.

Figures & data

Fig. 1 XRD patterns of alumina synthesized at 150 °C for (A) 6 h, (B) 12 h and (C) 24 h, each calcined at (a) 500 °C, (b) 700 °C, (c) 900 °C, (d) 1000 °C and (e) 1100 °C. (▴): γ-Al₂O₃; (•): θ-Al₂O₃.

Fig. 2 FTIR spectra of the samples synthesized at 150 °C for (A) 6 h, (B) 12 h and (C) 24 h, each calcined at (a) 500 °C, (b) 700 °C, (c) 900 °C, (d) 1000 °C and (e) 1100 °C.

Table 1 Textural properties of alumina synthesized at 150 °C for 6 h, 12 h and 24 h, after calcination at 500, 700, 900 and 1000 °C each.

Reaction time (h)	Calcination temperature (°C)	SBET (m^2 g^−1)^a	Vp-Total (cm^3 g^−1)^b	Dp (nm)^c
6	500	428	2.86	34.8
	700	257	1.64	34.8
	900	179	1.46	35
	1000	142	1.29	35
12	500	393	1.11	3.9
	700	216	0.73	3.9
	900	109	0.63	3.7
	1000	80	0.57	3.7
24	500	366	0.79	3.9
	700	187	0.53	3.9
	900	103	0.62	3.7
	1000	70	0.56	3.7

a BET surface area.

b Total pore volume.

c Pore diameter (BJH desorption).

Fig. 3 Nitrogen adsorption–desorption isotherms and pore size distributions (PSD) (in the insets) of the samples synthesized at 150 °C for (a) 6 h, (b) 12 h and (c) 24 h, each calcined at 500, 700, 900, and 1000 °C.

Fig. 4 Low-angle XRD patterns of alumina synthesized at 150 °C for 6 h, 12 h and 24 h, each calcined at 500 °C.

Fig. 5 FESEM images of alumina particles synthesized at 150 °C for (a) 6 h (b) 12 h and (e) 24 h, each calcined at 500 °C.

Fig. 6 FESEM images of alumina particles synthesized at 150 °C for (a) 6 h, (b) 12 h and (e) 24 h, each calcined at 1000 °C.

Fig. 7 TEM images of alumina particles synthesized at 150 °C for (a) 6 h, (b) 12 h and (c) 24 h, each calcined at 500 °C.

Fig. 8 Schematic representation for the formation of nanostructured mesoporous alumina.