Afterwards, the product was soaked and boiled with 3 mol/L
HCl for 1 min. After cooling under room temperature,
the product was washed and boiled with deionized water
till a neutral pH. Then the product was dried in an oven at 110 C to
a constant weight. Finally, B–SBA–K was grounded and sieved
through a 200 mesh sieve.