שמות ל,א: וְׁעָשִיתָ מִזְׁבֵּחַ מִקְׁטַר קְׁטֹרֶת
In the previous Parsha (Terumah) the various furnishings of the Mishkan were discussed (the Ark, table, Menorah, outer Altar) whereas the inner, golden Altar was not included, and only introduced at the end of this Parsha, after discussing the clothes of the Kohen.
The Sforno explains this seemingly discrepancy by noting the unique role played by the golden, inner Altar as opposed to the outer Altar where the animal sacrifices where brought. The goal and purpose of the animal sacrifices was twofold: to bring about the dwelling of HaShem in the Mishkan and to bright down His glory so that He meet with the Jews.
Whereas the golden Altar is only is only used for incense with the sole purpose of honoring HaShem. Thus, the section about the golden Altar was separated from the other furnishings. As stated in the Tanchuma the incense offering does not come to expiate sin or transgression or guilt. It only comes to bring simchah (joy and happiness).
